The hitcher basically caused his own death. Trying to flag them down initially was a judgement call. Having made the decision to attempt that and failed he should have let it go. Instead he stayed on the same road in the open after the car had passed. He can't have stayed alive this long without knowing sound attracts walkers. The sound of the vehicle alone would have attracted walkers to the road just as sure as if the car had them on a tow line. He added to his predicament by following along the road and shouting a second time when he saw them again.
I understand he made the decision to flag them down initially, but the man needed to face facts. 911 is down and probably won't be back for a couple of centuries if ever. Don't do the stupid thing, just rely on yourself because you can never truly rely on anyone else in life. God helps those who help themselves.
I agree with this even though I was not at all comfortable with how they zoomed by without even remarking on this guy. I understand why they did it and don't even diasagree but it was still awful. But that's the difference between thinking with your head and your heart.
The hitchhiker should have shut up and gone into stealth mode as soon as the car passed by. But we don't know how long the guy had been on his own. Maybe he was crazed by loneliness or felt he could no longer survive alone.
IMO part of Morgan's problem is that he is so alone. We humans are social animals, evolved to live in groups. It keeps us grounded. Even the loners amongst us are not really alone 24/7 for long periods of time. To go for weeks and months on end without seeing another living human being, in the horror that is the ZA would help to drive anyone crazy.