If for whatever reason you never wish to interact with #Threads, you can personally block it for your account. This hides all posts and profiles from Threads, prevents anyone from Threads from following you, and stops your posts from being delivered to or fetched by Threads. Simply click the "Block domain threads.net" option on any Threads profile or post you see in Mastodon.
@Gargron I guess my only criticism about this post is you didn't use the word "Threads" enough