The writers fucked up.
Ponn far has a telepathic element and holograms are telepathically null.
Of course Tuvok also said that you can work your way through Pon far with meditation which is code for masturbation surely?
So the hologram could be seen as masturbation plus, rather than sex minus.
Although if he could frakk anyone, cheating on his wife with a hologram, fuck it, this would have been an excellent opportunity to bring back Jennifer Lien... because he had been resisting his attraction to her forever... Of course half way through the sex with a Kes lightbulb, it turns out to be another Seska time bomb worm virus, who takes the ball and runs with it... Them?
"Look, I'm dead and I've lost, you probably killed me, I get it, you're the good guys and I'm the bad guys, you won and I lost and nothing I can ever do is going to be enough to put you assholes in the ground but here's what I'm thinking now, if you're still alive now, then I was wrong and you were right and you're going to make it all the way back to the Alpha quadrant and I should have just kept my mouth shut and kept with the program, so I'm sorry I was such a bitch trying to kill you all the times I tried to kill you, but since I'm dead and you probably did it, and like I said if I try to kill you again you're just going to weasel out of my devious trap, I say fuck it, it's time for a parade, I'm a loser, I should just give up, is spite all I have got going for at this point years after my bones have been... I don't want to even think about Kazon Burial practices, unless you left me behind in the boondocks with those thug savages, but here's my revenge, I'm Cardassian without revenge I might as well be a dead woman, well I am a dead woman but here's my revenge, you Mr Tuvok are going to spend the next two hundred years lusting about the memories of tonight were I took you to the unforetold heights of ecstasy and... You're going to fall in love me Tuvok and it's going to kill you because what i have between my legs and how it's going to grip your lovegun and pull the trigger is going to have so much recoil you'll be flinching for the next 3 months, and frankly right now, in the state you are in, bloodfever crazy fluffed up by the kiddy porn elf you're just going to have sex through my clothes because no force in the universe is going to stop you from treating me like an extremely fertile woman tonight."
But then he kills her which flips the telepathic switch and Tuvok is normal again.