Dad gets mad at adult daughter for turning guest room into nursery for their newborn, preventing him from being able to stay with them during visits: 'He said it was selfish [...] to keep an office [...] over a [guest] room'

Having relatives stay with you is difficult for everyone; the person visiting is displaced, and the person hosting has their life and normal routines disrupted with someone else always suddenly present. And in a small home or an apartment you really begin to feel the effects of this. This is further complicated by the needs of any babies, children, or pets who live at home with you, adding another often less predictable element to the mix. The trade-off is that you get to spend a whole length of quality time with someone whom you probably don't get to see quite as often as you used to, and it's impossible quite to get that same quality time and break through the ice to that "lived in" type of feel if they're staying elsewhere in the city. 

So, while it might stink that you might not be able to stay with your new-parent adult children in the way you could before, and you might find that fact disappointing, making the situation about yourself is just the wrong way to go about it. It's pretty clear that this father's accusations of selfishness are actually just a projection of his own self.