New neighbors and trimming a bush

Sorry if this is wrong place to post. It's about an old rhododendron bush, not a tree. The original rhodo bush is at least 20 years old (predates my ownership of the house). It had mostly died off but still had some of the old "skeleton" left. A newer central stem, seems healthy, has shot up and is about 5 feet tall with some smaller branches coming off of it near the bottom. I have been meaning to trim the old skeleton down but have needed to get some larger tools as the old branches are very very thick.

I have new neighbors, not met them yet, they just closed on the house less than a week ago. As far as I can tell, they did not get a survey done. I came home from work last night after dark, took the pup out this am and noticed that the majority (but not all) of the old dead branches have been cut off. Maybe with a hatchet? Not all of them were cut and they were all just left laying there. I have no proof that it is the newbors (other than I literally don't know who else would care about how it looks?) Any suggestions on how to broach the subject? I haven't dealt with new next door neighbors since I moved in forever ago.