@Halli
I never use a passport id to setup my wechat account. I just used my phone number, which is registered to my wife's Chinese id now but wasn't connected with any id originally.

@Napolean. I agree wechat isn't checking for illegals. But it could if it wanted. Political dissidents end up with a visit by plain clothes psb when caught posting statements on weibo or wechat. Illegals just don't warrant such scrutiny or on psb radar. But if that were to change, you could be sure Shenzhen based Tencent would assist them in anyway or with any request to track people down.