MIL has forbidden DS to call for his friend when we visit

[Hellotodays]

The in laws (who live close by and we see regularly) have told DH that our 6 year old should not go to call for his school friend (who lives next door to the in laws) when we go to their house this Sunday. His friend is a girl the same age and her sister plays with them too who is 8. Since they started getting on very well at school they have occasionally called on each other when we have been at the in laws. It's only happened twice in about three months as they are not often home when we are there. The parents are really nice and tell me he should come over whenever we are there. Last time they even let him join them for dinner. My in laws are not so welcoming and though the kids go back and forwards between the two houses the in laws seem a bit annoyed when they are at the in laws house, and this time ahead of our visit they told my DH that he shouldn't go there and we should just have time as a family. The problem is that all the other kids at the family gathering, including our youngest are a lot younger and the in laws don't really play with him, it basically means he gets bored of playing alone of me or DH have to keep him busy. I'm quite annoyed that they have said this to DH. I'm probably not going to counter it, but if it gets to a point tomorrow where he is bored and everyone else is just doing their own thing then I will tell him yes if he asks to go and play. But I'm just wondering how others see it? Thanks!

Op I'd go round later, you are both working, so weekends are precious.

MIL we'll be round a bit later we are going for a swim, walk, shop etc first.

I will be easier to arrive later than leave earlier

I went with the title, MIL trying to prohibit him from 'calling for his friend' ... which suggests she's also trying to ban him from going next door, playing at their house, in their garden. She wants him to sit in her house all fucking day while she doesn't engage at a child's level ever.

For context we are there one day every other weekend and the visits are the whole day - about 10.30-5pm or later

I have always absolutely loved my grandparents, but this is overkill. No wonder he's bored.

An honest conversation about everybody’s expectations of the visit would solve this one, with compromises on both sides.
OP we are working grandparents, currently recovering from an overnight stay. If you listen to the situation from an older person’s perspective and remember this could be you 20+ years down the line, it might help? A powerful image.
Personally I’d reduce the length of the visit and frequency, for your sanity! Tough gig X

miserable old buggers. why not be happy that he is happy.