Where there's smoke there's fire, good way of putting it. With a screw in it like that, what else has been 'homesmithed' on? Stuff like that screams of 'more' elsewhere.
There ain't nothing wrong with homesmithing, I've been doing it for years, besides it keeps real gunsmiths in business fixin my screwups.
Seriously, everytime I've got a project gun or a "all ya gotta do is fix this" gun it has cost me more in the long run than if I would have gotten one that didn't need something or several somethings fixed.
The guy probably jacked it up trying to get the original safety screw out. Those things suck. Wish Mossberg wouldn't make them so difficult to remove (they use a weird screw that doesn't fit a screwdriver). I finally had to use a counter bit and slowly removed it (after destroying the original screw). Replaced the whole assembly with a Vang Comp safety. Much improved. [Broken External Image]
Like gsarg notes, the safety is held on w a screw and it sounds like they "replaced" it.
A 500A with wood does look pretty classy.
I wouldn't give up on the project, but I'm kind of a Mossberg fanatic.