There is no specific IAAF/AIMS road race rule requiring disqualification here.
Comes down requirements for the specific event - and Race Director's discretion, should an issue be noticed or protested.
In those cases, circumstances, intent and impact are principal considerations. A single foot plant a few inches off the roadway does not reasonably indicate gained advantage. And, as another noted, vision on that corner was obstructed.
Road race courses are measured .1% long - the prescribed distance was covered and then some.
Disqualifying this dude would be utterly absurd - and that precedent would seem to require thousands more to to DQ'd.
In the same race, two runners helped a guy with cramps hobble-jump to the finish... which IS a clear DQ... don't see anyone complaining about it.