I’m not sure I’d call them all excuses.
I think it’s possible that some of them were real reasons, but as a result of one reason or another he concluded the conversation would never reach a conclusion and would just go in circles of unresolved disagreements. I don’t think this is uncommon dealing with people generally, so I think it’s possible he concluded it was happening again so there was no point trying to address everything or keep discussing.
More generally I have a guess that there’s a reason for leaving CF (though I don’t think it’s specific to CF, rather any in-depth discussion) that may be behind some of it:
Thinking that some people will argue pointlessly or endlessly in circles for the sake of it
Having some idea about indicators in a conversation for someone who is arguing pointlessly/endlessly
Possibly a root cause behind that is getting overwhelmed. Having big complex discussions is hard work, and “it’s just going in circles” is an out to avoid an overwhelmingly complex discussion.