There is no ''saving Luke'' amp in Rebels. Its supposed to be read in a thematic sense, not related to power levels. The same ''saving Luke'' Obi loses to Vader in ANH.
That said he stops at OWK Obi, but would beat Rebels Obi.
Director said SWR Kenobi was unbeatable in that moment, I don't see why it should be any different than Twin Amp, as for the ANH, Vader didn't know anything about Luke in that moment, Vader probably thought he was just another smuggler like Han Solo, there was no talk about Luke during the ANH duel, vs. Maul, Maul sensed that Obi-Wan was protecting Luke.
Also, since Yoda is not a darksider, he will be hindered as if he was fighting his former padawans like Dooku or Ahsoka, thats surely a big factor.
Maul was tired and weak.
And Vader as Yoda level is an informed attribute.
Clears. Twin amp is close but still Yoda
Did you consider that Yoda is hindered in this battle since he is fighting his former padawan?