I am intensely skeptical of her story.
That said, many of the points people are making in response are pretty weak:
1. Receipt: Why are you up in arms about her failure to show us a receipt at the press conference? This isn't court. I presume she offered something, like a Square receipt or credit card record, to substantiate it during her appeals. But who cares if she showed the public a slip of paper (particularly a restaurant receipt, which could be easily faked) yesterday?
2. Roach Coach: It's hardly irresponsible to eat at a food truck these days. They're often gourmet or close to it, particularly in Portland.
And many of them claim to use hormone-free meat, which would reassure me as an athlete. It's easy to say "be responsible for what goes in your body" on a message board. But I don't think that's realistic in practice. Athletes are people. They go out with friends and eat delicious things. It's silly to blame someone for taking part in a commonplace activity like that (if you even believe her story about the truck, which...).
3. She should've tested the meat: no. No way did she know about the positive test until all of that day's meat was long gone. Any follow up wouldn't be relevant enough to be useful.
Again, I have trouble believing her story. But none of the above points are convincing.