Probably because no one has any interest in seeing some (assumedly) overweight 30-ish fellow try to keep up with a team of badasses.
Even in some fantastical world where this did happen, he'd be killed shortly after hacking into the Enemy's network, followed by the cliche line, "I'm in."
Or the lesser used "We're in."
The first Predator was awesome, Predator 2 was okay but all in all I liked the idea behind predator 2 more than the film itself. I'd say they haven't done anything good with the film franchise since.
I'd love to be wrong - But I'm not expecting much.