I almost can't believe I'm posting on this topic.
All venue operators (and for that matter promoters) are obliged to carry out a competent Risk Assessment. Where a risk is identified they need to take 'all reasonable steps' to mitigate that risk. If they do both of these they will (in all likelihood) be shown to have shown 'Due Diligence' if they are sued by someone being injured in their venue / event.
Their only defence otherwise is to try and prove that the risk was not apparent to them and wouldn't have been foreseen by any other reasonable person in their position.
Councils therefore have seen the injuries / the claims / the increase in insurers insisting on an written policy on 'prevention of slips, trips and falls' and made the judgement that the only reasonable way to mitigate the risk is to ban talc.
I think if a promoter has even read this topic they cannot say they are unaware of the risk (albeit a small one) and so if they condone (or do not show due diligence in preventing) the use of talc they shouldn't be surprised in venues pass on any liability to them. And given that most are not covered by public liability insurance any damages would need to be met by them personally.
You can have all the opinions you like about it helping some people dance, being 'part of northern soul' (whatever the hell that means), ruining carpets, chairs, records and equipment or the impact on arthritic knees of it being banned; as you like. It all comes down to who pays the compo if someone is hurt.