Well there actually is already a SCC decision on the issue if a handjob is prostitution found here:
https://www.canlii.org/en/on/oncj/d...earchUrlHash=AAAAAQANYmF3ZHkgY2hpc3ZpbgAAAAAB
The key finding:
[28] Considering the facts before me, as I have found them, I am not satisfied when applying the community standard test that the act as described in this proceeding constituted prostitution. I am not satisfied that the Crown has shown the activity, using the community standard test, constitutes acts of sexual gratification in return for the payment of money.
[29] The payment of money as I have found it was for a full body massage.
The act of masturbation was optional, at no additional fee. Indeed, I wonder, and am left in a doubt as to whether or not the community might consider the act of masturbation in all situations to be sexual. One only needs to look to the conduct of a certain president of the United States and the response to activity that he participated in to wonder whether or not the act of masturbation is indeed in all circumstances a sexual act. Given that the act was done in private, as part of a massage, participated in voluntarily by all individuals, and a fee was paid regardless of whether or not the act took place, I am not satisfied that the Crown has met its onus and that the conduct constituted prostitution.