Was it a heated garage?
If not, the interior of the garage will stabilize at or near ambient outside temps. That means if it was -15 outside, it was either there or close already inside the garage and the pipes would already be frozen.
If it was a heated garage, unless the pipes were without insulation it is still unlikely what you did actually caused the freeze. They would have to drop from their temp all the way to well below freezing in that time to cause the ice to expand enough to split the pipe. Once you closed the door the temp would start to rise and prevent anymore freezing, or at least in a very short order.
But you need pipes to freeze SOLID so the action of the ice expanding would split the pipe. Even if it froze some small section some amount, I'm just doubtful it would have caused a hard enough freeze to cause the ice to expand so much as to split the pipe.
I suspect it was simply a matter of coincidence or at worst, what you did simply accelerated a situation that was going to happen anyway.
as to the guys motorcycle engine;
what doe he mean it froze it? I don't know too many bikes I can't ride in the rain without harming them. It the bike was deluged, given the short time involved, I still can't see it causing damage. Now, if water somehow entered the cylinder or crankcase and then was allowed to freeze, sure, it can do the same thing to the cylinder or case as it does to a pipe BUT, how would it freeze? Sounds like if anything he may have caused the damage himself.
The claim of damaging the motorcycle is very suspect.

