Well I don't use it negatively me54. I use it as a descriptor if/when I use it. Out of interest, what else do you think would be as straightforward a group name for Corbyn's close followers and admirers but would count as calling by a name rather than "name-calling"?
I don't know what you were taught Bags but I was told you should call people what they choose to be called. If someone calls themselves a follower of the Gruffalo and terms themselves as a Gruffaloist then it is fine to use it. If they have clearly told you they are not, or not told you they are and you persist in using your 'descriptor' of them then those who brought you up did a bad job and you would be being bad-mannered, impolite, discourteous, , presumptuous, uncivil, disrespectful, unmannerly, unpleasant or any other version of 'rude' they feel applies at the time.