Never said he was gong for a challenge ;) plus if he was wouldn't he let his team mates know ? Plus triple capping can make you LOSE the game as you muck up the spawns so there's no point in doing it unless the clock is ticking down and the scores are even which is the ONLY time you should triple cap ;)
in previous games i would never triple cap because you wind up loosing all three by doing it. in this game however, the spawns are so horrible and objectives are for the most part completely ignored in matches that with the other team only killwhoring in order to get all their killstreaks for the 2nd round.
i will triple cap by myself while everyone else is running around like idiots, wind up with anywhere from 6-12 caps/5-10 defends and we usually wind up winning that way...
....despite them having lodestars dogs warthogs and r2d2's all over the map the entire 2nd round....
I play a lot of Dom and have since the gametype was created. Although I understand your perspective, in my experience the easiest way to ensure a win is to control the board and controlling the board is much easier capping only two flags- particularly if you are facing a good, organized team.
Triple capping flips the spawns, you are likely to simply start trading flags and a decent team can quickly get the upper hand and evaporate your lead (a group of randoms not all that likely). I would get irritated if I had a teammate trip-capping wiithout a heads up as well to be honest as there is little upside.
The problem with what you were doing is the team you were with probubly had minimal gun skill to deal with the spawns flipping. If I know I am playing with a mediocre team, I just stick to B the whole game and rack points that way. Triple capping leads to havoc an unstructured chaos.
Now if your playing with great teams, you may get the request to not cap A or C and make the game last the full time. Ive done this and racked up over 12000 score in my best games. This occurs from having vsats and counters up 95% or the game and just stomping on anyone who joins in the lobby.
Anyway, dont be selfish. Just try to work with your team especially if you are winning by as much as you say. SPM has no effect on making the game last longer unless the other team quits out.