Because the other son’s wife has probably given them a hard kick on their arses and they know they wont go anywhere with her. So they come to you. Why did you give in to the whole naming thing? YOU get to name whatever you want to name the kid, that is shared with the husband. At the end of the day, NO NAME goes on a ID card at the hospital unless both parents agree. PERIOD.
So, you shouldn’t have given in. Compromise with your husband and find a name you both like and tell the parents later.
You just need to lay down the ultimatum to your husband, which you already have. If he tells you that you can leave, either you leave, or you stay and keep doing things the way you want in a stubborn way and live a parallel life to these morons you’ve married into, or you bend to their way.
If you follow the last option, they will be stepping on you the rest of your life. Some women may use that to their advantage - ji aap ko tikka pakana hai aaj - there is the kitchen jee, go ahead.