Did the teacher realise he was crying?
I can imagine saying something like 'sit up and get working' if a child had their head on the desk without realising they were crying. Obviously once I'd realised I'd ask them if they wanted to take a minute outside.
Toilets are tricky at the moment - we've restricted access except for medical need because of covid, so I can imagine not letting them out for a tissue too (if I hadn't realised they were crying), I usually offer blue roll instead. It's a long way round the one way system and we have to be careful of lesson changeover for other groups.
Obviously, some teachers are arseholes, or possibly under a lot of pressure right now, but if the teacher wasn't aware of the significance of the date and hadn't actually realised DS was upset I can see they might have been harsh without realising the gravity of the situation.
The year 7 comment is a bit off, did the teacher say 'stop crying, you're y7 now' or 'sit up, you're y7 now'? Former, probably an arsehole, latter, possibly a bit stressed right now, and not at their best.
Either way, worth a conversation with the teacher, possibly HOY if they obviously knew he was crying, and therefore an arsehole.