There are others who advert their goods and services all the time in this forum, some with links to their products sitting right in their signatures.
Personally, I would think that Cakewalk would
love to have a professional trainer who uses and trains on their flagship product put it out on their forums that such services are available. If anything it means that through said services their existing users will become more intimate with and more knowledgeable of their products, thus ensuring continued patronage from them (and certainly new users along the way).
They must feel differently about it, though. Go figure.
I would argue, however, that if they are going to disallow the placement of goods and services in posts and signatures that they disallow it for everyone. But this isn't my forum. :)
Seth