In the post-race Zoom I told Grant that USATF rules say you should run in a "direct" line to the finish while World Athletics rules do not have that stipulation. I asked him if that meant athletes should not drift out. His reply is below but he said it's good racing, should not result in a DQ and even if it did mean a DQ he wouldn't want to win that way.
"I don't think it's illegal to drift out. I mean, I guess I don't write the rules or anything. But that's just what happens on the homestretch. If you watch most any race, you come off the corner. You have momentum. Generally people are passing you on your right hand side, you naturally kind of drift out and then it's also a good strategy to drift out force people to run a little longer line. I mean, sometimes it backfires. And someone sweeps up the middle but generally people flare out. That's just how racing is done. In my opinion I don't think that should be illegal or you know, is grounds for dq even if it was, that's not how I would want to win on a dq like that. So yeah, I mean, if I were on the inside lane, and I felt someone on my right hand shoulder, I would also drift out. It's just how you race."
Video set to start at that part:
https://youtu.be/KiXgUj8Ua_w?t=483
(He also talks about it at beginning)