The In-Laws were being exposed to risk anyway via childcare for OP & her DH. Presumably it was all ok then (why?), yet we've had almost a whole year of Covid restrictions.
There'll have been times when the children were at school, in a classroom with loads of others, then at grandparents for evening and/or weekend, surely? So risk was brought to the home.
Is it a case of uh-oh, just had a thought about vaccine but, still want to use you for childcare. Have the vaccine and if you don't, no more shopping for you and you (suddenly) can't see your grandkids. No pressure or anything...
Covid Vigilantes are going to have a field day in months to come although I don't entirely believe they'll challenge people in real life. Only online.
We live in a Democracy. I doubt (unfortunately for the Vigilantes) you'll get your wish of 'vaccination mandatory or we'll make you a pariah'
Loads of people banging on in arrogant forceful fashion that everyone MUST have the vaccine or they're fucking stupid/idiots/insane isn't helping matters
DM was very undecided. We had a long productive chat about it on the phone this morning. She's now very likely to have the jab. There's no need to go in all guns blazing, authoritarian my way or the highway fashion.