Given the load that latch is supposed to bear, I'd be very wary of any repair, for the reason you cite. Bondo would be the definite choice over a wood filler, but I'd be worried of it being too brittle and/or breaking away from the rest of the wood once stress is put on it.

But...

If you find and use longer screws, you can probably sink them into the meat of the bottom board on the head. So use your filler for cosmetics, then drill new pilot holes of sufficient depth. Make sure to use pilots so you don't split the plywood. Install longer screws, and you might end up with a stronger latch than the original.

That's my first thought anyway. There's probably some cabinet repair threads here that might have other / better ideas.

Hmm, that's a good point. Yeah I put all the head bolts in my machines so I'm not solely relying on that latch either.

But OTOH, you ever notice just how desperately the head wants to flop forward when you have the light board swung open to put the bolts in? One wrong momentary thump or slip enhanced by a weak latch could spell disaster-a-la-Murphy...