The signal handler in this case is CPython's internal signal handling system thus any such onus falls on us...
The great signal handling hack of "set a flag that the interpreter loop checks on occasion" trick lasted a long time, but our VM has since evolved to be much more complicated than every bytecode being a safe interrupt point.
FYI - Most of the in-room conversation we tried to capture on this issue thread was at the core dev sprint a couple years ago (Sept 2017). It'll similarly take me a while to swap this context back in.