If 50% of the recruit's work will be with a different team and function, then you need to have your recruits be interviewed by someone in that team as well. That could be by having 2 interviewers, or an extra interview stage.
In your case that has a huge benefit, because
if the other teams manager is going to be a jerk to them, the candidate will have a chance to find out.
if the candidate is endorsed by the other team's manager, they will be much more likely to back up their decision by not sabotaging it once a recruit begins work. Right now they have no motivation to do so. Having agency and a hand in a decision makes people feel more responsible for it, and more likely to be unsupportive of things that undermine it.
You can throw things into the interview which will be picked up by the other team's manager and may, given the context, be taken a bit more seriously, even though they are completely normal things to say. For example, "The culture in our teams vary. John here is best places to describe that for his team, do you want to say a few words, John?" Or "If we make an offer after the interview process, John will be your liaison for integration with and working within his team, won't you, John?"
Right now it sounds like the other team will just get whoever is recruited, foisted on them. They have zero motivation because they don't have a say in (or any kind of part ownership of) the process.
So this recruit will be an "outsider" to them... and a part of what you're describing is going to be relayedrelated to the subtle walls and hostility of an entrenched insular clique brushing off and ripping down outsiders. In that context, anything that can be seized on, will be. By making the shared ownership of the decision explicit, that frame gets challenged.
As an aside, if their manager says "no way, has wrong body parts" or "I'm afraid they wouldn't fit in", that gives you a perfect opportunity to point to the technical and other merits, and begin a process where they can start to see the problem, or the issue becomes made explicit between you so it can finally be escalated to HR or someone senior, in a useful manner.
At the least, you get a chance to explain the problem in a context where it needs to be raised (and can legitimately be raised again if you feel they are acting wrongly and exposing the company to risk) instead of over 10 minutes lunch when it can be forgotten soon after.
At a pinch, if still not happy they are doing right, or they're fudging their replies or minimising the issue, you could even follow up by email, "John, I'm far from happy with our conversation about the recruitment shortlist. As you will recall..." and set it out, including their responses, and "Because of the concern of legal exposure if we do this wrongly, I have CCed this to/I'd like input from..." (HR, someone senior, legal team if you have one?) to force the issue, and again, its legitimate and effective, but you couldn't do it over a casual lunchtime chat so easily.