OP, the people who are giving you hell and calling you judgemental most likely mix with the same calibre of people in their social circle, and don’t see anything alarming or unusual in your description of him.
People having lower standards for their daughter’s potential partners doesn’t make you a snob, based on that alone anyway. They say you can’t judge a book by its a cover, which I’m not entirely disputing of course there are always exceptions, but they also say a picture paints a thousand words. Remember, we have not seen the photo, the OP has. Photos can also give insight to individuals based on their facial expressions, demeanour, and how they choose to dress themselves.
I live in London and encounter a diverse mix of people from all walks of life daily. Social and life experience has taught me to spot someone ‘rough’ or ‘trouble’ a mile off. Just like when police release mugshots of individuals who have committed crimes and it’ll generate hundreds of comments along the lines of “You can tell he’s guilty”. (And yes most of these individuals fall into the demographic of; unemployed, no fixed address still with mum, heavily tattooed)
Don’t pretend we don’t all recognise it, or that you’re so much more open minded and enlightened than us who don’t defy what we see before our own eyes.
All that being said, we can all be wrong. Invite him over for an informal drink or dinner, and access his attitude to life and towards your daughter. Your gut will confirm.
(Yes I’m a bit of a snob and I don’t care 🙂)