Babywearing parents of velcro babies who hate the pram/stroller - how do you handle grandparents insisting on using it?

Give me your best lines, arguments and assertive phrases that you like to use when a family member questions your decision to babywear or, like in our case, insists that laying flat in a pram is much better for the baby's development than being carried around and contact napping.

More context:

I'm soon going to visit my family (they live in a different country) with my 3 month old son. Me and my husband are almost exclusively babywearing, since this is the only way to make him nap and he will only tolerate his pram for about 10-15 minutes. Doesn't matter whether it's continously moving or not. My mother doesn't get it and insist on using the pram, constantly asks why we wouldn't put the baby in it and why we babywear and "destroy LO's back and spine". Her opinion is that the baby should get used to it, so we're doing it wrong when we don't keep pushing and letting our LO cry when he's in distress in said pram. I'm afraid my grandparents and other family member have the same view.

Additionally, my mother is a physiotherapist, so her angle is that what we do is bad for LO's development and he would benefit from sleeping on his back in a pram instead of contact napping. My hill to die on is that he benefits more from feeling safe and having a secure attachment to us thanks to babywearing.

Now, my toxic mother and my struggle with firm boundaries is a post for a different sub, but I would like to hear what lines or arguments work for you in such situations to just end the discussion without having to justify or defend yourself, so I can be prepared. If you know any studies or other science based facts regarding babywearing, even better!