I want to know your logic if you answer the 2nd solution.
AFAIK, In fact, there are no special rules for abbreviations, usually abbreviations are used to make pronunciation easier
If Bitcoin uses the abbreviation BC, BC is more popular as the abbreviation Before Christ
So bitcoin is abbreviated as BTC because it is easier to call and is not affiliated with other abbreviations that have been used previously.
So bitcointalk can be any abbreviation, the important thing is that it's easy to say and that other people understand what we mean. Or is it better not to use abbreviations? lol