Is this normal?

Yes this is normal and he should continue going unless he has a fever or severe cough. We started giving our toddler a prebiotic along with vitamin spray. I would also discuss with his family doctor.

Did they think he was very unwell for the full 10 days because that could explain why they’d say that’s not normal?

It’s so common for kids to get sick a lot when they go to daycare, the kids all give each other the illnesses they get, I’m shocked they actually told you it’s not normal.

My son picks up viruses back to back and almost constantly has either a mild runny nose, sneeze, or cough due to being in a daycare-like setting which is normal. To be kept home for 10 days, I’m guessing he was very sick though. Does that happen often? If so, might be worth getting him checked but if it’s only here and there that he has a virus with bad symptoms that can be normal. To be sick for 10 days though you should definitely get a child checked though to make sure they haven’t caught some sort of secondary infection which needs antibiotics to clear.

It's totally normal for them to get sick a lot in childcare. Kids are gross and share their germs a lot.

I'm assuming he wasn't terribly ill for the full 10 days? If he was then I agree with the daycare that that isn't normal and is something to investigate.

If he had a runny nose or a cough and you were just being extra careful then I wouldn't advise doing that. They're fine to go in like that. It's just a part of life when using childcare.