From what I have known,Mike and Sara were never in a serious committed relationship. They were more of a fucking buddies. So asking for a DNA test before signing a birth certificate is not a wrong thing to do. "The cuckoo laying its eggs in other birds' nests to spare itself the effort of raising its own young" - this is situation most men are afraid of i.e. raising someone else's kid without realising the kid is not theirs but of some other man. But once the paternity is established,they have to take responsibility of the kid which I think Mike is doing. If Sara is depriving Mike access to their son, then Mike will be compelled to go to court for sole child custody. Joint custody will not work out if the parents dont have good relationship.Now it is in court's hands to decide who will get Maxwell's custody.
I know this will be unpopular opinion over here since they will always be a gender bias. Moms are always innocent victims,dads are always dickheads/playboys especially in out of wedlock pregnancies. Also there is this notion that playboy men can't be proper fathers. I don't agree on that..