So in VTM:20th edition
Page 269 states with regards to a vampire using the kiss:
Once the Kindred breaks her vessel’s skin with her fangs, that vessel no longer resists the vampire (if he did in the first place).
It's even specified as part of the bite combat manoeuvre on page 276:
A player can declare her vampire’s bite to be a “Kiss” attack. A Kiss is resolved in the same way as a normal bite, but inflicts no health levels of damage. Upon connecting with a Kiss, the vampire may begin to drain the victim’s blood at the normal rate, and the victim is typically helpless to resist (see p. 269 for specifics).
The specifics being the quote on page 269 with the added addition of a willpower test for vampires allowing them to resist diablerie.
When performing a kiss on a frenzying vampire is the victim vampire still rendered helpless by the pleasure of the kiss? Does being frenzied offer protection to the affects of the kiss?
The pertinent rules would appear to be on page 298:
All difficulties to Dominate or otherwise mentally control a frenzied character are increased by two, and all difficulties to resist the effects of such mental control are reduced by two. The character never needs Willpower rolls to accomplish a feat, because the rage fueling the vampire’s actions is both a catalyst to heightened state of mind and a barrier against unwanted intrusions.
The combat systems including the kiss (Page 271) and the earning blood pool (page 269) rules are separate from the feats listed in the dramatic systems (Page 257) presumably to prevent frenzying vampires from succeeding in every combat encounter from force of will alone. Does resisting the effects of the kiss count as a feat?
My solution in play would be to allow it, at least long enough for other PC's/NPC's to restrain the frenzying vampire, being kissed doesn't take the vampire out of Frenzy afterall. Meanwhile the kissing vampire begins the process of becoming blood bound to the frenzying vampire. Which in it's own right introduces some interesting situations going forward.