but contradicts with #4.
The US consulate general may deny your H1 application but it shouldn't take away of your existing I-94. Only the custom or airport people should do so.
So with a valid I-94 (valid for 30+ days) + a valid passport, he can always come back with a new visa or not. That was why I said driving to Canada is important.
BTW, I believe you need to make visa appointment nowadays. Good luck. The GC is a pain on the butt.