The second person (I think) referred to the thread in the screenshot when they said "I saw it disappearing live". I have no problems believing that the guy deleted that thread, it's an off-topic thread. What I have problem to believe is that the guy specifically deleted comments from queer folks (which is the point of this post). And again, the person who started the Mastodon thread is someone that - in my view - has no credibility at all, considering the completely dishonest way in which they carried out the conversation.
Not sure what the screenshot you posted is supposed to prove. He closed a thread on the kagifeedback site asking to move the discussion (if needed) in Kagi Discord, where - in fact - happened (although with very little benefit for anybody). AFAIK it's not "his personal Discord" server, it's Kagi's server, and I believe most of the conversation (including the one in the "incriminating" screenshot) happened in #general.
I am really not sure what your point is.
Either way, it doesn't matter what I believe. What I know is that the person making the Mastodon thread is someone in bad faith and with (in my opinion) completely bad takes. Someone who makes such a post, in my opinion is a moron.