I may be reading this incorrectly, but if you are actually deleting inactive accounts and all their historic tweets, I would STRONGLY urge you to reconsider.
Letting people know how many “active” followers they have is good information, but deleting the output of inactive accounts would be terrible. I still see people liking ten year old tweets I made, but the threads are already often fragmented with deleted or unavailable tweets. Don’t make it worse!
Some may scoff at any allusion between Twitter and ancient libraries, but while the burning of the library of Alexandria was a tragedy, scrolls and books that were tossed in the trash just because nobody wanted to keep them are kind of worse.
Save it all!