Not just for early access - I'd say do it for 2-4 weeks from Early access start date. Gives all paying customers a chance to complete the MSQ and have a good run on the game before trial accounts are allowed back in. It may also deal with some of the RMT bots that use free trial accounts.
I was reading another suggestion on a forum the other day but it would be very unpopular - a mandatory session kick after 8-12 hours. Though it would stop the afk'ers getting around the auto logout, and allow a greater selection of people in, I could see a lot of complaints from those that are fortunate enough to have that much time to play the game. Unfortunately there doesn't seem to be a sure-fire way to make everyone happy but disabling free trial for a few weeks would certainly help in my opinion.