While there is obviously a level of frustration at the seemingly blunt removal of someone who has been around for a while, whatever one might think emotionally, these boards are owned by a successful business in Internet Brands. One hopes they control their businesses properly and as they (or their appointed officers) have taken a decision to completely erase all input over many years from GTE, they must think there is a very good reason to do so.
However, I think it would be good customer relations to explain why this action was taken (in broad terms if necessary) so that other long term contributors can make their own minds up as to their continued involvement.
The final post from Prune Towers looks to have been written in a rush and is highly questionable in that it mentions the importance of anonymity whilst itself twice breaks such a convention.