Bottle fed two year old

So I stopped breastfeeding pretty soon after my son was born because I didn’t make enough to satisfy him. He did formula up until a year and moved on to milk. It was easy to transition him to a sippy cup and I threw away all of his bottles. Well my in laws who watch him during the day, give him a bottle at random times during the day. Just the one either morning or night usually. He will hold it up and drink out of it like he does his juice or adults would sip on a bottle of beer (if you can picture it.) my husband and I ask “why is he using a bottle?” When it’s been no issue for him to use a cup. Both my in laws keep saying “it’s okay because we breastfed the boys for as long as this, it’s the same.”

Well I disagree. It’s not the same if I’m not breastfeeding him. I think it’s a bad idea because of 1) my pediatrician said to let it go at one of his various check ups as a baby and 2) I’ve only read it’s bad for their teeth!

Am I wrong for being a little pissed off that it always turns into “well it’s okay because babies breastfeed at two years old.”!?