I can't really agree with you here. If the airline gives you a boarding pass with a departure date of 9:30, and tells you to be at the gate by 9:00 (boarding pass said boarding starts at 9:00) , it's not your fault if the plane has already left at 9:00, and the airline better does whatever it can to get you to your destination quickly.
Well, that's not how it works. Passengers are required to be at the gate, ready to board. Delays don't absolve passengers of that responsibility.
The OP checked in at the airline ticket counter two hours prior to the original departure time. Since the OP hasn't returned to answer my question ("where did they go?"), we can only speculate about where the OP was when boarding was called and the flight departed. They really should have stayed close enough to the gate so that they would receive updated info.
As for the SSSS -- I don't think this was an evil plot. He got a last-minute one-way ticket on a different carrier. Of course he'll be SSSS'd. Happened to me as well, and in my case the atmosphere between me and the check-in agent was very pleasant.
Sure, the new booking caused the SSSS to apply, although the OP didn't say they ended up on a different carrier (only that they forced the agent to find them a seat on an earlier flight than the 12 hours later flight).
But what you and everyone else replying to this thread have forgotten is that the ticket agent could have overridden the SSSS and printed a new BP without it. So, yes, the airline employee "caused" the OP to suffer the full treatment, since the employee could have exempted the OP. I've got no proof that the employee thought it throught like that, but the OP suspects it and my guess is that the employee took some pleasure in it.