The RD also has a race to protect and without "definitive proof" he'd unleash the fury of Ashley's followers. He's in a tough spot, there's not much he can do. I'd imagine he wishes it went away but he's kind of stuck.
If you were familiar with the race, which I'm fairly sure you're not, you'd know where those volunteers would be, where the RD would be, where Ashley was, who was there to witness her (nobody!). His position is the official company line. That's pretty much it.
If you want the opinion of somebody in the know who is incredibly well respected with this race and in the ultra running community, go take a look at what Harvey Lewis is saying. He doesn't have to protect the race and it's pretty clear what he's saying.