I don’t believe number of players changes the chances of Long John winning. Long John progresses every time any player takes a turn. Two searchers instead of four just means each searcher gets twice as many actions before John breaks out of prison. With more actions, though, each searcher will have more private info.
They seem to have designed it so that Long John will be left with a sliver of space just as the last moment. That’s a pretty tight calibration that is a praiseworthy design. Still, I think you need to give the player who is up against a whole team of opponents a greater advantage. Pro searchers will rarely/never lose at hide and seek games. If I had my way, beating Long John/Dracula should be hard like beating Super Meat Boy. Possible, but extremely difficult, and you players lose most of the time.
I know I hate optional rules, but maybe you need one to make it harder when you know players are pro.