How is that stupid? Vader's suit has endured considerably more than Dooku's lightning without shorting out (Starkiller's lightning), and given Vader's lightning tanking feats, he should be more than capable of enduring Dooku's lighting long enough to bring his lightsaber in front of him in defense or disrupting Dooku's attack with a TK strike.
Since Gillard confirmed Mace to be level 8 duelist, and only bordering level 9 (canonically, due to Vaapad and his incredible amp on Sidious), Mace lost his only advantage over Dooku in terms of statements in Legends. They have very similar statements in refrerence books, perhaps with small advantage for Dooku. As does showings.
And Vader at that pint, is just a crippled half-droid-half man, shadow of his former self.
Dooku>=Mace >> Vader
TK is the only thing, that might save Vader from humiliation. He wasn't even able to defeat TPM Maul's clone. many minor Jedi gave him hell. He dies first. Dooku is marginally more skilled, but he mightt be a bit tired, before Vader will fall. And that might give Mace that small advantage he needs to.
Mace or Dooku, Vader is outclassed
Yes, we all could see how great Vader's stamina is. Espiecially, when some Djem So user with great raw power in the Force is charging at him. Oh, and that guy is inferior to a guy who was charging at Dooku in the same way... And Dooku wasn't nearly lying on the ground before fight was over, Anakin had to outmaneuver him.