As near as I can tell, the rules don't say anything about what line cars must take under a yellow flag. They do say cars must slow down to an unspecified speed as enforced by a pace car (don't know if there's a pace car in a sprint car race), but there is definitely no passing permitted.
A new NASCAR rule has been added which prohibits drivers from exiting disabled cars and wandering around on the track, unless there is an immediate risk of fire or explosion (rare these days). Apparently, this wasn't in the rule book previously because no one thought that a driver would be stupid enough to do what Ward did, but they didn't take into consideration what being high on pot might do to a driver's judgement.
“A new NASCAR rule has been added which prohibits drivers from exiting disabled cars and wandering around on the track, unless there is an immediate risk of fire or explosion (rare these days). Apparently, this wasn’t in the rule book previously because no one thought that a driver would be stupid enough to do what Ward did, but they didn’t take into consideration what being high on pot might do to a driver’s judgement.”
I think IMSA has also added a rule to this effect. Prior to that, the rule was that drivers were expected to obey directions from race officials (which can be anyone from the race director all the way down to a corner worker).
Having driven a race car myself, I do know that if your car is disabled (fortunately I haven’t had that particular pleasure in a race car, although I’m sure I eventually would if I had the budget to keep racing) you are much safer in the car than out of it while the course is hot. Basically, you don’t get out of the car unless it’s on fire or you can easily get to a safe location, such as the “cold” side of a wall or a fence.