What does vitiate have to do with this? Palpatine could blitz nihilus before the latter can even react, Palpatine most definitely has a good chance of winning.
Sidious knows the technique to block force drain. He taught it to Dooku who used it to activate the Dark Reaper and be safe from its effects. Ulic and Nomi also knew this technique.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
The Jedi Sidious blitzed were still able to lift their lightsabers and prepare for him before he struck. I see no reason Nihilus won't be able to simply raise his hand and use the attack in the same way.
Because Nihilus is as unknown as Vitiate in terms of lightsaber use? We know from his confrontation with meetra, that his first instinct is to drain his enemy, so I don't see him raising his blade before the confrontation ends. And yes, Sidious does know how to block the force drain technique as well.
__________________ ”You presume limits to my power. There are none.”
Make what up? The Dark reaper is a weapon that drains your opponents of their life energies, like Nihilus. There's a technique that blocks it. Anakin mastered it when he was a padawan to destroy the dark reaper.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
Unless you can prove the property's are the same, it's irrelevant. One type of drain isn't equal to another type of drain. Nihlus' drain is otherwordly and unless there's proof that it can be blocked (there isn't), move on.
Lightsaber? He just has to raise his damn hand. Plus he's used the Force without even gesturing so he could slow Sidious down that way or possibly use the drain without even gesturing.
Actually, it's you who has to prove the types of drain are different. Drain works on the same principles, who or what performs it is irrelevant.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
Anakin learned it from the spirit of Ulic qel-droma. Dooku learned it from Sidious.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
But this is untrue, because Vitiate's drain left the planet without the force, Nihilus' drain just leaves a wound in the force, etc. So looks like the onus is on you, not that it matters in this debate anyways.
There are different levels of power for drain, not different methods since they all do the same thing, which is well drain life energies. Vitiate>Nihilus in drain through that ritual of his. And Neph, yes he did.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
But he did. He learned it from Sidious which is why he can activate the Dark Reaper for a while without worrying about getting drained.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."