Okay, I just re-watched the scene and actually, it is canon. 😮
YouTube video
The reason being I believe is not solely because it isn't contradicted by anything, however. I should point out that, because I still don't agree with "if it isn't contradicted, it's true". It's canon because after the cut away (1:07), which occurs immediately after Anakin and Obi-Wan enter the room from the hallway. When it returns, we see Anakin putting (not already having it applied) Obi-Wan in a choke hold and does not have his lightsaber in hand. Obi-Wan loses his lightsaber after Anakin dropkicks him (1:23), but at 1:32 we can see Anakin pulls his lightsaber to him. Obviously when he put Kenobi in a choke hold, he wouldn't stash his saber away, so it must not have been in his possession. The novel then gives us the reason as to why Anakin doesn't have his blade there.
However, to True Jedi, this just shows that Obi-Wan wasn't trying to kill him until after 1:07 in the duel. Afterward, he is. As well, it still doesn't indicate that he could take Anakin head-on. Here's what it says:
"A roar of the Force blasted Obi-Wan back into a wall, smashing breath from his lungs, leaving him swaying, half stunned. Anakin stepped over bodies and lifted his blade for the kill.
Obi-Wan had only one trick left, one that wouldn't work twice-But it was a very good trick.
It had, after all, worked rather splendidly on Grievous . . .
He twitched one finger, reaching through the Force to reverse the polarity of the electrodrivers in Anakin's mechanical hand.
Durasteel fingers sprang open, and a lightsaber tumbled free.
Obi-Wan reached. Anakin's lightsaber twisted in the air and flipped into his hand. He poised both blades in a cross before him. "The flaw of power is arrogance."
"You hesitate," Anakin said. "The flaw of compassion-"
"It's not compassion," Obi-Wan said sadly. "It's reverence for life. Even yours. It's respect for the man you were."
He sighed. "It's regret for the man you should have been."
Anakin roared and flew at him, using both the Force and his body to crash Obi-Wan back into the wall once more. His hands seized Obi-Wan's wrists with impossible strength, forcing his arms wide. "I am so sick of your lectures!"
Dark power bore down with his grip.
Obi-Wan felt the bones of his forearms bending, beginning to feather toward the greenstick fractures that would come before the final breaks.
Oh, he thought. Oh, this is bad."
Alright, to analysis this information I dismissed: this clearly shows that Obi-Wan knew he couldn't stop Anakin head-on. He has to resort to a "trick" (fighting dirty) and forces Anakin's mechanical hand to drop his saber.
Notice that when Anakin says Obi-Wan is hesitating this is because he was talking rather than fighting. There was still a distance between them apparently. In other words, it was only a chance that he had to kill Anakin. It wasn't an opportunity that Anakin couldn't fight back against. This is obvious since Anakin does fight back and puts him in a choke hold, neutralizing that chance. There's nothing to indicate that had Kenobi immediately tried to do something, Anakin wouldn't have done the exact same thing, IMO.