As the skirmish option is not available for fellow guild members, shouldn't the assault option on the plunder screen be the same.

I was able to select the assault option on a fellow guild mate. I got as far as the fleet selection before I stopped (didn't want to take the chance of it actually plundering him), but I was under the impression that it shouldn't even get that far.

I just checked, same here. Last I recall that was not possible.

before it was possible and it made danger ratings manipulation easy then so it was foribbiden, rihjt now it goes to the screen of choosing fleet after that shows msg how that is not possible

Ok, still think that the option shouldn't be available at all, just like skirmishes.

depends on the point of view sometimes I use that option to set my fleet for instant attacking when I am taking part in the raid if my guildmate is on plunder board (Saving 4 turns 2 for patrol 2 for attack on NPC )