Very fair question, and I'll attempt to answer as clearly as possible.
For me, citizenship is something that cannot be considered lightly. I became a Canadian Citizenship simply because I passed into this world in Canada. Others earned their citizenship by immigrating and doing whatever it is they do to become a Canadian citizen. If we grant someone citizenship, and then that person goes to a foreign land, for example, and engages Canadian Forces as an enemy, then part of the pact we have with them as a citizen includes our right to try them for the crime of treason. I'm not a lawyer, but I believe that this is one of laws from the Criminal Code that can be applied irrespective of where they occur. (Lawyers? Correct me?)
Anyway, once bestowed upon a person, I believe that Citizenship should never be rescinded. Once an individual is Canadian, then they should stay Canadian. Even if we have to punish them (upon conviction).
One thing I would do, however, (if I were King of Canada), is to strip any other foreign citizenship. EG: no dual citizenship.
I know that this doesn't fully clarify my thoughts, but my feeling is that if we feel we can strip citizenship, then what's next? And for what reason? I just don't like the slippery slope that could be used to threaten people with. "If you don't stop, we'll take away your citizenship.."