The "better safe than sorry" approach towards signal handlers is to do as LESS as possible inside the signal handler and let the main program handle the situation.

That would be true if the signal handler was called from the actual signal handler Perl gives the system. This hasn't been the case since 5.8.0 (See "Safe Signals" in perl58delta.) Perl signal handlers don't even interrupt Perl opcodes, much less OS system calls.