Why bother?

Definitely set boundaries they have no “rights” as grandparents but as the mother you are their link to ur little one and if they want to build a relationship with him they need to also put that effort into uu… without uu ur son wouldn’t be here!
If one of your own family members was acting this way I’m sure you would set boundaries to… in laws or not respect is due to the woman who carried and birthed that baby! You are his primary care giver and if certain interactions make uu feel isolated or left out then uu have every right to limit or stop them!
Stick up for yourself you deserve nothing but respect especially in ur own home!

Why bother indeed. Like you said, your child is only going to get older and see how they treat you. If anything, they’ll probably chat shit about you around him, therefore encouraging him to also be disrespectful to you too.

What does your husband say about it all?

I was in the same situation but I told my partner to sort things out and at least be civil for our daughters sake as when she'll get older she would have awkward situations and weird feelings but it isn't her fault. So try to get your partner to step up cause you're the mother of his child at the end of the day x

Oh, sorry XX AND XY. I didn’t hear you when you said hello ☺️
And next time they come, say a bit after they get into your home.
Oh my bad, I keep in getting distracted and not saying hello back.