Prettybird said: "The OP has already explained that she put the quotes around "too tiring" because, well, she was quoting her MiL. Strange that, using quotation marks for a quote ."
But I think that people generally use the quote to denote they don't actually agree with what has been said... you only have to look at this use on this very page, so I guess that is why dollywobbles suggested the OP might be disingenuous. For example:
CookieDoughKid with "For my MIL, she finds my gc "tiring" yet can do two days worth of gardening back to-back "
and SirChenjin: "used to complain about being 'tired' when they came to visit" and her later sentence "I'm afraid I find his being 'tired' quite irritating"
Now, in those two cases, they might have reason to be irritated. But the original question is about a different case entirely, where the PIL have previously had the children for three days, and now find it's too tiring. Well, maybe they do find it too tiring. (And many people can't work to 60/65 now, let alone to 67, and certainly not at their former levels.)
People support their children in all sorts of ways, not just by childcaring. So if I were Rules' DIL (and I'm far too old!!!), then I would certainly see her point of view, just as I hope to be a hands-on GP... and my 12yo is certain she will never have children 