Haven't listened to the podcast, but did read the report.
Before I read the report, I had 3 possibilities in my mind based on the available facts:
1. Shelby doped intentionally using oral pills and mistimed her dose a bit relative to her testing window. Result: big ban.
2. Shelby consumed some tainted supplement (vitamins, protein powder). Plausible enough. Result: a ban, but a shorter ban. Miss the Olympics for sure.
3. Shelby consumed some tainted food such as the infamous burrito. Not very plausible based on reported levels, food/ag system in the US, available literature on dosing in case of boar meat, fact that she didn't order a pork burrito at all. Result: no ban.
As most know, intent or knowledge is not relevant in doping cases. It's only how the substance got there that's important. Evidence or lack thereof will help dictate which argument your legal team is going to go for. I am sure that Shelby's legal team tested all her supplements etc. to see what their options were. An unfortunate possibility here is that since contamination isn't necessarily consistent, they might have missed it if they tested a container/batch other than the one she consumed.
Since 2 was out, they decided to go with 3 even though the evidence here was pretty circumstantial and speculative. There was really no other choice because ignorance isn't a defence. After reading the report it becomes clear that 3 couldn't have happened even if she'd somehow gotten a pure boar burrito because the nandro was synthetic and the amount found would have meant she would have had to consume an unreasonable amount of boar meat.
Though intent isn't relevant in doping, most fans would view a person who got caught on 2 to be ethically/morally innocent. Even though Shelby's team didn't try to argue that one, the report does suggest that the amount found wasn't consistent with contaminated supplement. So while it's true that they might not have been able to test the specific batch of supplements she consumed at the time of the test, it's doubtful that any supplement would be that contaminated.
This, coupled with her sudden progression in her mid/late-20s after several years pro in the same group and doping rumours about her boyfriend at the time makes it hard to believe she is innocent from an ethical standpoint. I can understand why her former teammates and her friends still support her... it can be hard to believe someone close to you was so deceptive.