Any illegal being harbored at CX should be given the chance to return to HKG immediately, or find other employment. Then a massive new bid can take place throughout the system in order to rectify the current issue. Those senior enough to hold a base in their home country can certainly take any position available, and if an aircraft type change is required, use their joker. I guess then we would really be able to see how many Canadians are in US bases, and American's are in Canadian bases.
If you are telling me that those pilots violating immigration law throughout the system have done so without understanding the consequences, then I would respond to you that they should have read their contract and the basings agreement before bidding on a base. I realize these guys have families; so do I. Not only are they illegal, but they are not contributing to the tax base of the US government - something that those US citizens in HKG that want a base would be happy to do. Kind of like hiring a Mexican without a green-card as a nurse, when there are plenty of US citizen/green card holders that may be looking for a nursing job.
CX managers and CX are liable for harboring these employees as per the US immigration regulations. If they are not careful, some manager may be surprised when Swire does not come to bail them out; and some pilots may be surprised when the US government informs them that not only are they forbidden from entering the US and it's territories, but also that they owe $300k in back taxes, fines, and fees.
For those that are worried; look at the law, don't make excuses why you are special and can get around it. It's not going to be fun if you show up at work in the USA 5 hours before your flight, only to be informed that you are being deported.