Besides the specific reason why that policy failed for this particular panel -- you might just want to revise this policy generally? Substantial revisions also would usually imply a change in target audience, so this seems like it'd have a decent chance of resulting in panels that are unexpectedly much more or less popular than expected (I for one would have most likely indicated interest in a general panel for finding new fandoms, while 'not a c-drama' got marked as least interest)

If you're still planning on revising the panel, perhaps a panel on promoting small fandoms might be a good replacement?