Not really an assumption (big or small). They’re saying almost 3’ water depth (that is really good). Hopefully the generator allows operation at that depth also. But switching it off wouldn’t be a bad idea for a crossing.
I was actually wondering if it could do that. Say you’re crossing a fairly deep river. You don’t have a snorkel to protect the generator. You switch the generator off, cross through the river in full electric mode, and no water goes into the intake.