Wow, that anon was incredibly rude. But I find some of their points credible.
I don't intend to dissuade you as an author and it's absolutely up to the author to shape their charcaters.
I just want to bring up some context from canon for why Harry might not enjoy being called a whore or a slut.
Harry grew up in an abusive household where he was constantly insulted and belittled. He has an instinctive reaction to cruelty, because he spent years being humiliated by the Dursleys.
Degrading sexual terms would likely remind him of past mistreatment rather than feel playful or arousing. Like Marge calling his mother a 'bitch'.
Harry is fiercely independent and refuses to let others define him. In Prisoner of Azkaban, when Snape publicly humiliates him in class, Harry talks back to Snape, despite knowing it will get him into trouble.
In Order of the Phoenix, when Umbridge forces him to write "I must not tell lies" into his skin, again he refuses to back down, even though it causes him physical pain. He doesn’t allow himself to be degraded, even under direct authority.
In Half-Blood Prince, Harry openly challenges Dumbledore when he feels like he’s being left in the dark about Voldemort’s past. Even though he respects Dumbledore, he doesn’t passively accept condescension or secrecy. (This is in contention against that part when Harry immediately apologised to Dumbledore during that meeting in your story) Must I mention Harry thrashing Dumbledore's office?
Harry is polite often but he doesn't regret his snarky words.
Harry despises being controlled or having his agency stripped away. Imperius doesn't work against him and veritaserum likely wouldn't either.
Any attempt to degrade him through language like “slut” or “whore” would directly challenge his autonomy, something he has fought for his entire life.
He has a defiant streak that makes him push back whenever someone tries to reduce him to a label. If Tom, of all people, attempted to call him a slut or a whore, canon Harry would either outright refuse to engage or fire back in a way that shuts it down immediately.
Again, this is only meant to provide canon context and in no way intended to be offensive.
It's your story and your wish to mould your characters however you see fit. Because this a fic, and fanfiction wouldn't exist if everyone felt things were too OOC.
Hi anon! Despite my better judgment, and at the risk of beating a dead horse, here we go....
First of all, I want to stress that, for all we do see in canon, we do not see Harry have sex. Any fanfic author who writes such content must necessarily deviate from the scope of canon.
Now, there's an assertion here that if Harry were to "entertain" some amount of dirty talk (of the nature "whore"/"slut"), this would be an irrevocable departure from the independence/autonomy/agency he shows otherwise throughout canon. I would respond to that with the fact that real, breathing individuals are rarely so consistent in every facet of their lives. It's not entirely dissimilar to someone questioning why there are staunch feminists who like to have rough sex--with the implication that it makes them less feminist. It doesn't.
(Also, canonically, Harry ends up with Ginny. You're telling me she wouldn't ever boss him around in bed? Seriously??)
There's also some discussion here about Harry's past treatment making any sort of degrading sexual terminology immediately triggering for him. I believe--and hope--that "whore"/"slut" belong in an entirely different world from the Dursleys' traditional fare. If Tom were to call Harry a "freak" in bed, I might see your point.
"He has an instinctive reaction to cruelty" -- yes, Harry does. But also, Tom is cruelty. Cruelty is the only language Tom knows. On the one hand, Harry has only made so much progress in this fic because he has learned, over time, to pick his battles strategically. On the other: Harry has learned that Tom uses "whore" to describe him because Harry desires affection/love/connection. Since then, this word has failed to hold as much power over him -- because Harry does want those things and is not ashamed of it.
Tom intends to shame, but Harry doesn't feel ashamed. I think that's a critical distinction to note here! In many ways, I actually think this is Harry claiming power by seeing through Tom and resisting the shame the latter intends to impose, thereby simply enjoying the sex he's having. (Also, I hope you can tell that Tom is projecting in this scene. His inability to accept his own desires / desire for connection has him on the offense.)
Finally....if it's hard for you accept any of the above, I would encourage you to remember that Harry is also a boy having sex for (basically) the first time!!! What Tom says is, all things considered, of secondary importance to him!! Harry's not going to argue for a duel at dawn when they could instead be having sex....