Perfectly reasonable--the same thing RS would do (see: "Gnu/Linux"). Trademarks do not protect themselves. It takes a concerted effort by the trademark holder.
Good luck with that. If you look on a site like Stack Overflow at questions about even languages like C and C++, you'll see developers confusing Xcode with their language. With a name like "Visual F#" it must be 100 times worse since it includes the name of the language in the product name.
I get and appreciate the distinction, but I wish Microsoft would replace "Visual" as the brand keyword with something that doesn't evoke associations with Visual C++ for Win32 desktop applications or Visual Basic for Applications macro memories