Alan, you are correct. But it is the Dip to Black we are discussing, and of course, the Dip to White.
Transitions that do not need overlap (to use the term we used in the dark ages) or handles, should be allowed to operate without an incorrect error message. No more, no less.
It is a bug and has been reported as such.
Shooternz,
The message is certainly annoying, and completely unnecessary - in the case of these two transitions. Or any transitions that do not require handles if there are others I haven't thought about lately.
And as for the work around, I believe that doing it my way where I have a one second clip that eases into black and eases out, eliminates the entire transition thing anyway. It can be put over multiple tracks that might otherwise require nesting to accomplish the transition based task.