I'll be the jerk, for I don't care. But this, here, is where I feel no sympathy for the dad:
My little guy being 2.5 and wound for sound thought it would be cool to play with al the boxes and climb on them.
So he let's his little kid climb on things that aren't his (kid's or dad's) that are for sale to other people? Awesome. He probably sat there and thought, "aw, look at Lil' Bobby being cute!" Guess what? It's NOT cute. Keep a better eye on your kid. I wonder how the guy would feel if I took my 2 year old nephew into his house and let him just play and climb all over his stuff.
It would have been one thing if the kid accidentally brushed against it and the stuff happened to him or if dad didn't see Lil' Bobby doing what he was doing, but that's not the case. Dad stood there and watched his kid being mischievous. And I won't blame the kid, for kids will be kids. I'm blaming the dad for not being a better parent.
Parents like that piss me off for they think everything and everyone should cater to them or tolerate them because they have a kid. Guess what? We don't. It wasn't my choice that you had an off spring.
And yes, the store should have known better but at the same time they sell military surplus. USED things. USED MILITARY things. We all know the types of thing the military has access to and uses so let's not pretend it's a surprise. The dad should have known that not everything in the store is, was, will be clean. Hell I know that and I'm a 28yo non-mil person.
I feel for the kid, I really do...but...well...the dad is an idiot. I wonder if he knows what personal accountability is -- probably not.