Just to clarify, nuru is not a massage type for which an occupational licence, certificate, or permit is required. So someone offering nuru is not subject to having state permission to do it, even it it's globally recognized as being a form of massage.
Example: if you get a pedicure they'll also give you a foot massage, but they likely don't have a license to engage in massage. That doesn't necessarily mean it's illegal, but instead would depend on how the laws are written in that area.
For the physical contact between parties to be illegal sexual contact then it first must be sexual contact. Just having someone touch your clothed or naked body does not make it sexual contact - even if you have an orgasm from someone rubbing your feet like above might not be defined as sexual. Or maybe it is - check your local statues.
The original ad you mentioned was for a certain amount of time to be spent receiving a nuru massage, and nothing else. If you choose to view nuru massage as sexual then that's your own perception; if the two of you hit if off and decide to do something other than nuru massage (see a movie, have sex, paint pictures, etc) then it's separate from the nuru massage. The advertiser still has time commitments the same as you, so if you do expand activities then don't be surprised if the clock continues to tick along.
If you want to have some real fun thinking about this, how would the law define it if you received the same nuru from a male? Flipping situations around is a great way to reveal bias and discrimination, either in yourself or others or the law.
One last observation: you mentioned "nuru is not something you can legally buy." I dare you to try and buy a back massage from a licensed masseuse. You can't. However, you CAN mutually agree upon a rate for someone's time to be spent massaging your back. I know the wording may sound the same, but they have very distinct definitions. And nuances are important.