In all seriousness, @MrBig, I was kidding but I wouldn't personally care at all if someone brought a snake around their shoulders like that as long as they weren't letting it crawl around on food or whatever.
As far as worrying about if it's venomous, I'm not sure if you're serious about that but I also recognize that I'm a huge animal nerd and not everyone else is. There are maybe a [very small] handful of venomous snakes you would be able to handle like that without getting bitten, the overwhelming majority of venomous species are simply far too aggressive to drape over your shoulder and walk around with. Certainly none that you could readily find in the US with the exception of a hognose snake, but they're generally too small to carry like that anyway.
At any rate, that's just a [likely red tail] boa. They're completely harmless though they tend to get rather large.
As far as should it be in a grocery store? I mean, probably not, but I would assume if the store had an issue with it they'd ask him to leave or at least not to bring it back next time. Either way, it's a pretty harmless act.