Hi Byron - I don't think you can add it with only a template change; it needs to be added as vbulletin parses the bbcode into html. Here's a link for the mod in 3.0.X that can do it for all URL's:
https://vborg.vbsupport.ru/showthrea...threadid=74703
What I'd do is just add another clause to the if statement checking for >50 posts, and make it (user > 50 posts) & user != my posting bot user ID, or not in my posting bot user''s group ID).
You can mess with the if clauses to aim the nofollow parameter to as few or as many users/groups as you'd like.