Already been stated its a sucky mechanic and needs to change but it is not against the rules to attack a city in waves with its owner gone. Save your boo wooing and your anger and put it against blatant cheating the smoothrich way
You're right, its not against the rules to attack a city while the owner is gone, just like a bunch of exploits and bug abuses weren't against the rules in NA_1 back in the day... until we had to make rules for them cause people don't want to play fair... Nothing you are currently doing is against any rule per say; but going out of your way to prevent the owner from returning to
fix the problem and have the fair and appropriate battles we are supposed to have is pretty much abusing the bug, regardless how you want to justify it.
You're right, perhaps other clans would be doing the same if it were them; and I would be as equally disappointed about it either way. Just don't start complaining on the forums when another clan exploits a bug against your faction, because you've set a precedence and folks won't need to justify themselves when they just need to point at this example. Shame...
On that note; props to NH, Frisia and TkoV for being such great opponents to battle against. My catapult awaits!