[usurper]

The government has to let them back in.

Not so much, by joining a foreign military and taking up arms against the UK they have effectively taken an affirmative action to renounce their citizenship.

Under UK and American law the government can not strip you of your citizenship but you can loose it through your own actions.

[Former Proud Canadian]

Hey, I think these guys should be shot, but, have you heard of due process?

I understand and share your passion but you can't just declare someone PNG by virtue of a voice analysis of a video.