Why anyone thought that sig was fine Miguel is beyond me.
As for the problem as mentioned, it's not a difficult thing to have more restrained avatars and sigs for general forum use, whilst keeping NSFW content purely in the NSFW camp. There's no decrease in content; just a reallocation of where the content is placed. If it's an issue and you think you MUST HAVE and NSFW avatar or sig like the one Miguel linked (or a few others going around nowadays and in the past too), then I don't know what you expect to get out of a family friendly gaming site.