Screen time is screen time...if not used in moderation, sooooo many studies have shown a link between screen time and obesity and other not-so-great habits.
I'm not a "no tv/no computer" mom but I do firmly believe that, like pretty much every thing else, screen time should be used in moderation. Be sure you're also giving ample opportunities for gross motor development (i.e. going outside to run around and play), reading, writing, being creative through play/arts/crafts.
Personally, I believe that if you do decide to allow him computer time you need to monitor it and make it a 'team activity'. Don't plop the boy down in front of the computer as a babysitter - get involved too and enhance the learning/recreational experience.