I'm sure that's something that the local zoning office can work out :)
That's the thing: this case isn't about sex at all; it's about whether or not it's a business, and whether a business is allowed in that neighborhood. I know that most cities don't let you run businesses in your home (presuming you live in a residential neighborhood and not something zoned specifically for home business) unless it's got very low impact: no signs, no foot traffic, no impact on parking, no 'regular hours' (i.e., having a Tupperware party every Thursday at your house is probably against the rules; having one every Thursday at someone else's house [each time] is probably fine).
It seems to me like that's a business.
/jordan