Thor potentially getting his ass beaten by mooks or fodder like Corvus Glaive or Proxima Midnight instead of personally being beaten by Thanos himself is a point against, not in favor of him. Thanos personally beating him up is the most charitable interpretation for Thor, not for Thanos.
The idea that Thor would be inhibited doesn't have much merit tbh. Thor's lightning largely manifested itself in being wreathed in lightning, amplifying his physical strikes, and a few projectile attacks. His only really big AOE lightning blast I recall is when he first awoke them against Hela.
The only argument that has merit IMHO is that Thanos could have used the power stone, but given how Thanos casually dominated the Hulk (who was a peer to Thor at that point in time) in hand to hand and casually no-sold Thor himself, any arguments for Thor are honestly flimsy.
Russo makes it clear.
“He’s not using it,” Russo said. “This is to show that Thanos, the Genghis Khan of the Marvel Universe, he’s unbeatable in 1-on-1 battle. He’s conquered thousands of worlds. He’s a much more polished fighter than the Hulk, and Thor, and Loki.”