Unlike land-based meats, seafoods go through a process called "auto-lysing" which mean they dissolve back into seawater. They don't cause the colon plaque that land-based meat does.
I have to say I strive to be a raw-foodist vegan, but I've come to accept eating a little sashimi now and then for the fats/minerals. I do high-rise construction and winterime is just too cold otherwise. Also since I don't live full-time out of my garden anymore I noticed that I started feeling 'out-of-whack' by being dependent on store-bought groceries, and not having the access to sanitary weeds and wild-foods.
Like you initially I was turned off about the B-diet due to all the meat, but as I am a non-secretor there is a lot better diet for me.