The negative connotation of a crutch implies that you are past the point of needing it and should be standing on your own two feet. If a thing is not meant to be temporary, or if you'll never be able to perform a task as well without it as you could with it, then it's a tool rather than a crutch.

Thus, calling GLP-1 meds a “crutch” implies that they are unnecessary, and that the patient should be able to do it without medication, which then creates guilt and shame where there shouldn’t be any.