The term is used to cover a variety of meanings, eg:
a) someone who has never been in a cave before
b) someone who has been in one or two caves but doesn't really yet know their way around
c) someone who has been in quite a few caves but relies on someone else for routefinding, decisions on water levels etc
d) someone who is clumsy as hell and totally unable to get round a cave without damaging anything that can be damaged
e) someone who is perfectly able to take their own decisions and find their way around the cave without causing damage, but who doesn't do SRT
Equally, there are different reasons for wanting to know whether someone is a 'novice', eg:
i) the cave is delicate and easily trashed by the unthinking
ii) those on the trip don't want to have their trip curtailed because someone can't get past an obstacle
iii) the landowner doesn't like the idea of people coming to grief in his cave
I think 'novice' is a reasonable term for those in categories a and b, ie (relatively) new to caving. It ceases to be appropriate somewhere in c,, once someone is a reasonably competent caver but has not become used to organising their own trips. d and e is where we get to 'perpetual novice' territory.
It would help if we were able to distinguish between different types of 'novice'. Someone in a or b might be a lot better than someone in e at getting up and down climbs. Depending on the cave it matters whether the 'novice' you have with you is a good climber who has never been in a cave before, or someone who is completely at home in cold wet darkness but can't climb to save his life.
As to whether the term is patronising - I think there's something to do with the attitude of the people using the term. If all around you value technical competence above all else, then 'novice' can become a term of disparagement, rather than simply someone at the beginning of the learning process. We could use 'beginner' or 'new member', but wouldn't they end up with the same emotional overtones as 'novice'?