They have the right to reverse deletions, but it's a supremely bad look and if they're really doing it (this is the first I've heard of it) I hope they catch a huge amount of flack. There could be very good reasons for some of those deletions that might impact safety, job security, or personal relationships.
I manually deleted all my content on Wednesday afternoon. As of 8 am this morning all the comments were restored. So, yep, they're definitely undeleting content.