I'd been playing as Technician btw. It's a really fun class. There's a great sense of accomplishment in bringing downed defences up, and you don't even need to do anything to get kills if you place your turret right. Gets frustrating though when there are Infiltrators in the gen room and nobody's helping to defend.
The Gen is a tricky place. I don't go down there myself when I play as Heavy on Flag, and I generally see the Gen as far less important than the flag stand. A pair of well-drilled and well-specced Heavies can camp an enemy gen against multiple opponents, effectively drawing them away from doing something more relevant to winning the game, like offense or flag defense.
Generally, I'm all for an indoor brawl, but a Gen is not something that should be defended at any cost.