Cheating is cheating
As shown and stated above the two players in question were undoubtedly cheating, what would it take for you to cause more of a fuss about it? Just because it was $4 shouldn't make it any worse or better than if it was like mine a couple of years back, a $50 sit-n-go. Same thing, disconnected, by the time I got back I was all-in with the BB, it didn't take me a long time to get back but it was late in the game and I was chip leader.
The thing is if these two players were genuinely playing each other they would have probably seen the flop, turn and river so you wouldn't have lost as much and probably got back in time to still have a big enough stack to continue without worry. I understand why people do this but it is cheating and it's wrong, and yes it is a shame when nothing can be done because proof is required which can't be achieved if your disconnected, by the depletion of your stack simply tells
you they were colluding but that in itself is not proof enough.
A different point is about disconnection, I wish there was some way of researching this but i've had poker rooms disconnect me at certain times which seems, let's just say wierd. Not being disconnected from the internet, from the poker server, i've seen it a lot at certain places and it always seems to be at an important point eg: Holding the nuts on the river with more than two others in, or having just flopped the nuts. I've not seen it happen when i've had nothing, but then again that's a different story.
The thing is there are unexplained things which happen during a game of poker, there will be cheaters and there will be disconnects, I handle them like bad beats, it's happened so let's get on with the next game, dwell on it too much and it can effect the next game so just forget about it like you do a bad beat.
Knock em dead in the next game arkadiy, good luck