I think you should go on doing what you have already done.
In addition, it might be possible to prevent your DIL's parents from getting far on the critical track by saying at the first hint of criticism or the desire to discuss the young couple's careers or fianances something like, " Well, I know nothing about that, so I can't comment" and then move on to some other topic of conversation that has nothing to do with the family.
You cannot change a self-opinionated person of our age - only he can change himself, and he is not going to, as he is certain he is right.
Try to ignore his remarks, rather than take him up on them.
Depending on the dynamics in the family, I think I would mention my son that it embarrasses me when his FIL starts discussing their (your son and daugther-in-law's affairs) as they are adults and their affairs are not really any business either of you and your husband or of the in-laws, but that you feel it wisest not to enter into a discussion with them.
Presumably, your son's FIL has made his opinion very clear to your son and his wife and you don't want them thinking that you and your husband are ganging up against them.
How often and when do you see your son's in-laws?
If it is only in the young couple's home once or twice a year it should be possible not to get involved in discussions.
If you see them regularly as part of your own social circle, I would try to see less of them without giving offence on that account, obviously.
They don't sound like the kind of people you and your husband would choose to see regularly, so see as little of them as possible.
Booking Hotel Accessible rooms



. No good will come of warfare love and support your D in law and maintain the hugh moral ground.