So, trying on clothes is potentially shoplifting now? I mean, I can see the logic, I know what size I am and don't try things on... but that poses a serious problem for a lot of people.
Sure the manager could of handled differently... but if the guy is wearing the shirt, and in the store for a half hour... odds are near 0% he's a shoplifter. In a half hour, PLENTY of camera's have seen you, so its not like you can be an in and out guy, which is the point of shoplifting.
If I were the customer, I would file a complaint too, course, as a customer, the complaint would have been against the store/manager, and not some retail jockey employee. I would not even notice the retail employee unless they were following me, or made a comment that struck a chord on me where I would check their name tag and remember it.
I think there is more to the story than we are being told. But yes, I feel his complaint, valid. But as someone else said. Complaints against you, usually mean your doing your job right.
Trying on clothes isn't a sign of shoplifting. Heck, wearing them out of the changing booths might not be. But remember the original poster didn't say he'd alerted the manager after a half hour - he saw the person walking in the unpurchased clothes (quite possibly shortly after the customer exited the booth) and told the manager at that point.
Almost all of my retail experience was in grocery stores and I've personally been out of that for over a decade, so I'm not sure what the standards are for situations like this. I can say that if this is what happened, I'd have a huge problem with the manager, and if I had been the person who filed the complaint it would have gone to a higher level than the establishment itself (unless it's a single outlet, at which case I would have wanted to speak to a manager of a different shift). I agree that there could very well be more that we're not being told, but at this point I think I'd rather just focus on giving advice to the original poster and if the manager chooses to come on here to give the other side of the story, I'll adjust accordingly. ;)