In effect all bugs are security bugs. When people offer an excuse, what they're telling you is that they don't care about correctness, which in turn means they don't actually care about security only about appearances.
Why are all bugs security bugs? Because security depends on the actual behaviour of the software, and bugs cause this behaviour to deviate from your intended and documented behaviour in unknown ways which means they have unknown impact on security. Figuring out whether any user of the software actually incurs a security impact as a result of any particular bug is likely to be far more work than fixing it, so just fix it.
The equivalent of an argument that everything causes cancer => smoking is fine would be all bugs are security bugs => don't bother fixing the bug underpinning a known a remote code execution exploit.
Which is not at all what I was getting at. Again, don't spend time trying to argue why this or that bug is probably fine actually and not "really" a security problem, fix it and then it isn't.
Why are all bugs security bugs? Because security depends on the actual behaviour of the software, and bugs cause this behaviour to deviate from your intended and documented behaviour in unknown ways which means they have unknown impact on security. Figuring out whether any user of the software actually incurs a security impact as a result of any particular bug is likely to be far more work than fixing it, so just fix it.