I don't see why it's a hard one for people to get their heads around tbh.
My dad is/was an alcoholic, narcissistic, violent man who manipulated any and every scenario possible. He twisted me into hating my mother when they were divorcing, lied to me repeatedly, belittled me, hit me, made me feel worse than shit on somebody's shoe and then on top of all that, found a new Mrs, moved in with her forcing me to find somewhere to live within 2 weeks, and having a hissy fit when I wasn't in the mood to say goodbye to the prick after he'd made me cry THREE SEPERATE TIMES and shouting at me on the fucking moving day, IN FRONT on the moving men that were helping me and my new landlords who I was giving some of my furniture too that wouldn't have been able to go into my new room.
All of that's not even scratching the surface of what my actual childhood was like with him.
My dad to this day doesn't have my address and never will. I can't imagine I'll be telling him when I finally get pregnant either. I want my children NOWHERE near that man.
So no, it isn't odd for an adult child to not want a parent to have their address. And it certainly isn't "suspicious" in relation to the child. I'd be suspicious of the parent in question more than anything... People don't do this for no reason.
Not all parents are good parents, I'm glad that you haven't had to experience that to be able to day it's "odd" and "suspicious", but not everyone is as fortunate