it's the soft woven serger threads you need to avoid - the ones that are stretchy. Other "serger" threads are no different than what we would consider "regular". I use Maxi Lock the most with my LA, and it is sold as a "serger" thread.
I will add that most of what I've seen sold as "serger" thread at places like JoAnn's and Walmart is not very nice thread. But that is a different market than what is sold for more commercial use.