These are two different roots.
comes from root which means all or every,
and imperetive "kul" comes from root which means "eat"
I know.
But if you put the diacritics aside, your reasoning isn't so crystal clear anymore.
Despite the root is for eat, there are forms written , for the same word. But if you live in the deluded world of false diacritics this doesn't bother you I guess.
And eat something such as food isn't necessary for it, you can consume for example a topic or a even a book using the root, not literally of course, especially for the book or you'd probably have a very bad stomach afterwards. It means more like consume, such as you can consume food and you can consume clothes, or a false rumor can consume your intelligence.