If the reason the Titans or other heroes like Superman shouldn't be around to help in a Batbook is because they would solve all the problems in like 5 minutes, that's not a reason to stop the characters from appearing, that's a reason to create more complex problems for the protagonists. If Superman could solve all of Batman's problems for him, then those aren't very compelling problems. They exist in the same universe, there should be a reason they both exist and carry books. If you can't apply that same approach to Nightwing, then that's a problem with Nightwing as a character, an IP, or a book, and with the universe as a whole.
Anyways, there are several Super-characters around, all with super-hearing, so if you've been applying your suspension of disbelief to explain away the fact that they won't solve every character's problems within seconds because they're too busy with their own, I have trouble understanding why you wouldn't apply the same thinking to characters without super-hearing lol.
All that said, yeah this is nice fanservice. It's the kind that at least gives me a reason to want to read the issue, because now I'm hoping Taylor actually circles back around to Donna later on. We have Donna here, and we have Cass appearing in #86 because of Fear State, and both characters are sisters to Dick in their own ways. So if Taylor actually fleshes out/re-establishes his relationship to his two existing sisters well, I'll have much less of an issue with his new character.