It’s a tricky one, but ultimately there are always going to be situations that you don’t agree with. Same could go vice versa.
As per above poster, I’ve been in my stepchildrens lives since they were babies and although both sides of the families are amicable, there are still moments where we have to bite our tongue.
We’re currently all shielding at our house as I have symptoms. I feel guilty as hell because it means they potentially might not see their mum for a couple of weeks, we’re all stuck in and missing out on half term etc. But it’s just one of those things. People could catch this anywhere.
I don’t think you should stop him coming round but can you maybe try and limit contact while he’s with you? If you’re in a medium tier and have more leeway, can you go out for a couple of days to reduce the amount of time being spent with your stepson? Without making it a big deal.