Is this inappropriate?

i feel your pain. my in laws have done some stuff that i just cringe about. but this is a health risk. your baby could get sick! i would probably keep a binky on hand and when you see him going to put his finger in his mouth i would offer the binky. and just say he really prefers his binky. also if you want you might say that the doctor says(which im sure your doc has told you this) that babies at this age are at risk for RSV (something like that) which can be deadly and they can pick it up from people.