Thanks for posting.
Having not read 'Teaching..." I won't comment too much on the letter, other than to say it seems to assume a rigid view of the educational process. Perhaps the environment is less determined, and can support multiple analyses of power, ideology and 'eroticism'. Or perhaps not all educational systems participate equally in this complicity. This would call in to question whether silence is always equal to repression. Of course one could also say that the act of 'coming out' is useless as this action has already been co-opted and remains futile by its very definition of announcing oneself at the (powerless) margin.
As for your real question, disclosure is problematic to me because BDSM has not (yet) been viewed thru the same social lens as LGBT individuals. Although I would champion its inclusion, I think it is a much more slippery Identity, with far more shades of inclusion/exclusion. For the most, LGBT folks can each identify with a singular vision. BDSMers are all over the map (including LGBT BDSMers). Sadly, its almost as if BDSMers are still stuck in the 1950's while LGTBers move forward (of course no one is being billy-clubbed like gays in the 50's).
Disclosure to me, is not that important, but would be nice in certain situations. Using Queer as a signifier may be helpful, specifically in academia, but not that helpful 'on the street'.