They are in the public interest when their desire to keep such affairs and proclivities can be or have been used to coerce them into acting against the public interest
yeah, I read that this is a leak from the Torys, so it is used a leverage against those on it to ensure they tow the party line. Thats fucked up, blackmailing their own ministers.
mp's having alleged affairs that don't include a provable element of coersion or abuse, are nobodies business.
similarly those that enjoy the company of prostitutes or being pissed on.