Obi-Wan has dropped down to take Grievous by surprise, quipping and joking because he thinks he has the upper hand, then Grievous pulls out not one but four lightsabers and tells him he’s been trained by the guy Obi-Wan couldn’t defeat twice, and Obi-Wan is thrown into a difficult fight.
The problem is that it really isn’t a difficult fight. Just on the basic math of having one blade to block four simultaneous ones, Grievous should have been able to chop Obi down even with zero training, let alone with training from Dooku. But that nerdy nitpicking aside, even in the scene Grievous is clearly incompetent and Obi-Wan never seems to act threatened, smiling and treating it like a game until the fist fight later on.
In Hal’s commentary on the movie, he talks about how his editing of Grievous leans heavier into the reality of Grievous being the opportunistic coward that he is, rather than pretending he’s still the badass killing machine of the Genndy Tartakovsky cartoon. Removing that line here appears to be part of that philosophy, with Grievous just briefly trying to defend himself before running away almost as soon as he’s losing.
I think the best example of that approach, one of my favorite subtler edits in Hal’s version, is in Grievous’ first encounter with the jedi. In the original movie, when he shatters the window and flies out into space, he says “You lose, Jedi!” Then when he’s escaping in the pod, he says to himself “Time to abandon ship.” Both of these are pretty lame lines; the first because obviously Anakin and Obi aren’t in any real danger in the opening sequence of the movie, and the latter because it’s just stating what’s happening on screen. In this edit, however, the former line is now replaced by the second, so that he says “Time to abandon ship” as he shatters the window and flies out. This is a huge improvement, not only because it’s now actually kind of a clever one-liner, but also because it’s playing up Grievous as a sort of “Starscream” character who is perfectly aware and even proud of what a weaselly “survive at all costs” villain he is.