I don't think Jason committed suicide. His body would have more than likely been found by now and the time/situation at hand before he went missing doesn't equate to suicide in my opinion: he was called in to work early; by all accounts, he gladly agreed to go in early, got ready, and left. I find it hard to believe that along the way he decided "well, now is a good of a time as any to kill myself," even if he had been thinking about it (which from what know about the case, I do not think he was).
Also, I don't think his height would necessarily be a deterrent for a random abductor, particular one who stopped and maybe talked to him and realized his disability. Besides, hundreds of young, athletic guys have vanished in the last 15 or so years, so it does happen.
BUT, I do not think it was a random abductor (though I do not rule it out so easily). I have always believed that for Jason to vanish so completely without a trace, it had to be someone he knew or was at least familiar with; possibly even someone in the neighborhood/along the route he was walking. And this case is extremely frustrating because there is so little evidence to go on, so all we can do is speculate.