Grandparents might miss 1st birthday

So a little backstory - my husbands step father is basically his real dad. He considers his step father his father. My husbands mom also passed away 2 years ago but his step father is still very much apart of his and our families lives. His stepfather has since met someone else and they’re engaged.

So my daughter turns one on August 29th and we’re having a small party of 20 people due to Covid (which we’re allowed up to 50 people in my province if social distancing can be done) and we’ve told our parents and siblings about the party over 2 months ago.

Well 2 weeks ago my husbands stepdad and his fiancé planned a trip to British Columbia which they will be flying round trip from Ontario. They leave today and are gone for a week - making them home on August 15th. I made a joke yesterday about them cutting it close with having to quarantine when they get home with her party being their last day of quarantine. His fiancé then told me they don’t plan on quarantining when they get home because they’re not leaving the country and it’s not required. I said I would feel much more comfortable if they did since they’re flying and you just never know - plus my mom who is coming has kidney disease and is higher risk, plus a close friend of mine that’s coming is pregnant and has a small child as well.

Am I in the wrong for not wanting them to come if they refuse to quarantine?

I’m kinda pissed about the whole thing since they’ve known about her party for months and asking them to quarantine shouldn’t be a big deal. (She is unemployed and he’s been working from home since March).