A protester who heckled Shabana Mahmood said he came to the UK as a child from Malaysia, describing the home secretary’s claim that he was a white liberal as “laughable”.

Joe, 32, who did not wish to give his last name, migrated from Malaysia at the age of four with his family. He said the home secretary’s proposed immigration reforms would have left him, and thousands of children like him, in limbo.

“Imagine being a child growing up and not knowing whether you’re going to be deported out of this country?” he said.

Mahmood told “white liberal” hecklers to “fuck right off” during a live interview in central London last week, after protesters accused her of copying the policies of Nigel Farage’s Reform UK during an on-stage event.

Joe had told the home secretary he wanted to “personally thank you for out-Reforming Reform” before being escorted out of the room. Two other audience members shouted “refugees welcome” as he was removed by security.

The protesters were part of Green New Deal Rising (GND Rising), a UK youth-led climate campaign focused on engaging politicians to secure radical environmental policies. Footage from the action shows the room was dark. The campaign has released a tool, “My Map”, to support progressive candidates in the local elections, in a twin bid to tackle the climate crisis and fight the far right.

Joe pointed to recent statistics suggesting 90,000 vulnerable young people could be kept in poverty by Mahmood’s proposed changes to indefinite leave to remain (ILR). “It’s just cruel. And it comes from the fact that the Labour party is so desperate to get the heat off of their backs because they’re so unpopular.”

He added: “They’re willing to throw migrants under the bus to try to pander to Reform voters rather than actually trying to make any material change to their lives that would help ease the cost of living crisis and reduce inequality in this country.”

Mahmood told the comedian Matt Forde’s The Political Party podcast at the Duchess theatre, London, that claims she was chasing Reform votes were “just a way of delegitimising the point of view that I bring to the table”.

She told Forde there was an aspect of racism to the claims. “I do think there is that element of it, which is: ‘How dare you, a brown woman, say a thing that we white liberals think you’re not allowed to say?’ Well I’m saying it.”

Joe said the protests were about both the substance and process of her proposed reforms.

The home secretary plans to end permanent protection for refugees, who will instead have their asylum grants reviewed every 30 months and be forced to return home once it is safe to do so.

Refugees will not be able to bring their family to the UK until they can afford to live self-sustainably, and refugees will only start to qualify for permanent settlement after 20 years.

Mahmood also plans to double the time it takes for most overseas workers to gain permanent settlement in the UK from five to 10 years.

“She is pushing through these cruel immigration policies that are separating families, deporting children who are born here in the UK, and are making people wait up to 30 years for settled status, which is absolutely insane,” Joe said.

He argued it was sad that instead of engaging with these critiques, one of the most powerful women in the country had chosen to “resort to childish swearing and personal identity attacks that aren’t even correct”.

He hit back at Mahmood’s characterisation of him as a “white liberal” with no skin in the game.

“It is incredibly laughable that she waits for me to go outside of the theatre hall before she says this,” he said. “She’s calling me, a person of colour, a white liberal. But what she’s doing is incredibly illiberal.”

He said citizenship had changed the trajectory of his life. “The fact that I had been allowed to come to the UK and that I had been able to become a British citizen has meant that I’m somebody who is contributing in taxes. I am involved in civil society, volunteering, and giving back to the community in both tangible and intangible ways.

“This is indicative of migrant communities who come and give the UK colour and vibrancy.”

Joe said he heckled the home secretary after exhausting what he saw as the usual democratic routes, including writing to his MP, signing petitions and responding to consultation forms.

“I’ve not heard back from my own MP for the last three or four emails, and nobody else in our south-east London organising team has heard from theirs,” he said. “We feel completely shut out of a national conversation, pushed to the point where we have to do things like this to have our voices heard.”

He said GND Rising remained committed to campaigning on the climate crisis and migrant rights, insisting the two were deeply connected.

“It is us in the global north that are producing [green house gases], which will disproportionately affect those in the global south the most.”