After rereading the OP, it seems like the correct response is to find a different linkshell, actually.
HNM shells will usually demand that you level up jobs or bring specific jobs because their goal is to burn through as much content as fast as they can and give out prizes for those who participate the most.*
Social linkshells are usually more willing to accommodate fun jobs in both serious and not so serious content. Usually.
If your linkshell is saying "we don't want your WHM in our plasm farm" then you seriously need to get a different linkshell.
* Except for those drama filled shells that have cliques and favoritism and the LS leader gives all the stuff to his in-game girlfriend who is really a guy but he hasn't figured it out yet