Here's two additional reasons why she shouldn't be considered in the mix with the women's "elite" category:
1. Drug Testing
She was not in the drug testing pool. The usual protocol is to select the top "x" men and women + a random few (chosen a head of time) in the order that they cross the finish line. No way am I saying that this particular athlete would have a problem with drug testing, but because she could not be identified as the fifth place women overall, then she couldn't be tested.
In addition, a female runner in the 2:50+ range who has a break out performance may not know all of the drug restrictions and could end up in an embarrassing situation if she is on some medication for a health issue. This actually happened at a major marathon many years ago when they decided to drug test through the 25 place female finisher. The athlete was a prominent local professional who suddenly found herself at the center of attention because of illegal drug use when all she was doing was taking a legitimate medication.
2. Refreshment bottles & other benefits
Elite athletes are afforded many benefits that the other participants don't get - heated area near the start with food, lots of rest rooms, space to warm up, etc. that would give them an edge but the main thing here is that they are allowed to have the personal refreshment bottles. Obviously this is a huge benefit. So, now you are thinking - well she really belongs in the top 5 because she had a disadvantage. But even if she did for this one issue, then she could possibly protest that she should have been 4th, 3rd, 2nd, or even first because she wasn't allowed the same as the other athletes.
We actually had a similar issue at the Olympic Marathon Trials many years ago. Someone from the organizing committee determined that only the "B" qualifiers should be allowed to have their person refreshment bottles. I had that changed immediately to allowing everyone who toed the line that day to be treated exactly like everyone else during the race. Just think if the 4th place finisher in the Trials was not allowed to have his/her own refreshment bottles. I would not want to be the Referee or on the Jury for that protest!