if attacking them is going to help you win then go for it. There are several scenarios in which this would be the case.

1. They have small stacks that you can take advantage of to expand your territories

2. they are blocking critical points from which you could be attacking the other player

otherwise, it would be pointless to attack them if they weren't going to attack back. IMO its 'acceptable' to attack a flagged player, but in some cases just not smart.

I would definitely attack the flagged player. They have taken third place. In most cases, it wouldnt make sense for second or first place to attack each other and potentially lose ground.

If there are 4-6 and a few have flagged, that is a different story. Flagged and away players make good barriers.

I'll attack a flagged player if they are in the way of me getting to an unflagged player, regardless of whether I'm in the lead or not. I will also attack flagged players who attack other players if it suits my needs at the time. I am less likely to do that if the flagged player specifically says he's flagged to me, or he doesn't attack anyone else.

If he is going to finish third anyway you might be helping him if you take him out so he doesn't lose domination points (if that is the way it works)

it's always okay to attack a flagged player if it helps your game.

flagging is a courtesy - it helps the game end faster. i'm personally happy to leave the flagged alone to thank them for their courtesy when possible.

but if killing a flagged will help your position you should absolutely do it.

flagging means "i'm done!", and that's all it means. no one who is flagged should cry about getting attacked.

i guess i am just unclear on the ramifications of flagging. will i gain more points if i flag and stop playing, or is it better pointwise to keep playing? or does it differ at all? confusing.

I don't have a problem with any aspect of the game changing once a player has flagged. All it means is that they're happy for the game to end. If they attack with it, or are attacked with it, there isn't much of a problem from my perspective.

If its strategically beneficial to attack a flagged player, go for it.