i think you're overthinking. plenty of people drop threads here without it being a specific i don't want to play with you situation. as long as they didn't tell you to fuck off and just ghosted, then it could be anything from them no longer feeling that character, just losing interest in the thread, getting busy...

if it comes up you play the character just be chill and say you do. there's no reason to bring up the thread you previously had or anything. i don't think it's sinister to not bring it up if you're playing entirely different people with them currently.