I've just been replaying the game, and it is fairly apparent that the stranger, as he sounds on the radio, is being played up as some insane stalker psycho, clearly evident by the sound of his voice.
Yes, I'm sure they probably hadn't yet cast Anthony Lam when they were making Long Road Ahead, but he sounds really different (creepy, and with some kind of accent) on the radio (at times, sometimes he sounds kind of normal, but still not how he does when we meet him).
When you meet him, his voice sounds quite normal (noticeably different if you compare it to ep 3). Maybe Telltale tried to fool us into thinking he wasn't as crazy as he sounded. I don't think the radio was distorting his voice either.
Could they have had more sinister plans for the Stranger, and changed him at the last minute? It could be a reason why the episode is shorter than the rest (I am also aware that the shortness could be to make things seem more desperate, represent the situation, etc).