No one is "middle of the road" on slavery. Either you're completely and entirely against it, or you're a piece of shit.

I disagree: anybody that is "in the middle of road" and is holding that "slaves benefited from slavery" is anything other than racist drivel

is lying to you. They are not "in the middle of the road"; instead they are racist assholes that hoping for, at best, an excuse and more likely are just enjoying wasting your time.

There is absolutely nothing to debate.

These debates aren’t about what’s said but about who “wins” and the person who “won” is dependent on what media outlet is covering it. If you’re so middle of the road that you don’t know who to pick, you’re going to watch a debate?

Who is still on the fence about whether slavery was beneficial to the slaves? Who would that debate be for?

The "middle of the road" position is that slavery was a centuries-long atrocity. Anyone who thinks otherwise he is too far gone to be worth trying to persuade of anything.

FYI I upvoted you.

I get your intended idea, but in this case, what is there to debate about slavery = bad?

Anyone “on the fence” about that is just a bit too far gone for common sense, let alone words/a debate to reach.

We already had the debate over whether or not slavery was good. It happened between 1860 and 1865 and the "wasn't good" side won.

If your mind is in the middle of the road about slavery benefiting the slaves, you should volunteer to be a slave, just to clear that up for you.

Couple of years on a prison chain gang ought to do it.

That's how slavery in America was first abolished, right? Well, nvm that it wasn't really considering the prison industrial complex.

I'm a lefty that does appreciate debate in certain contexts, which seems to be somewhat unpopular nowadays. There would be no benefit in having a debate here except maybe in a very, very, very, very, very, very contextual, academic forum of a thought experiment (and I'm highly skeptical of even that, as you would have to presuppose some truly monstrous things).
Desantis is not going to be in that forum. He's going to platform KKK rhetoric used as a justification for slavery for nearly a century after its abolition. His staffers are quite literally Nazis. The ethics of chattel slavery are very clear cut, similarly to how the ethics of sexual abuse are clear cut: for all but an infinitesimal section of people, the only people advocating for them are monstrous, disgusting bigots.

if you aren’t sure that slavery was a bad thing, it’s pretty clear what side you’re on.

After that should there be a debate about whether slaughtering babies and raping women might not be pure evil?

That would be a bit redundant since they should be covered as part of the 'debate' about whether slavery was beneficial.

There's nothing to debate.

And when one party is playing by no rules, there's no discussion.

Is anyone really undecided about this topic, still?

If so there are far better ways to reach them than pretending both viewpoints are legitimate. You really have to get to the crux of the issue and people have to really grok what life is like if you're not white, cis, het, etc.