I feel very badly for Hee Seo. She's been such a trouper taking on so many performances, filling in at the last minute for all these cancellations, which must be incredibly physically demanding and exhausting...and yet, she's incurring the wrath of so many simply because she's "not Osipova" or "not Vishneva." So many performances may not have happened if she weren't ready and willing to fill in when others could or would not. She may not be Vishneva/Semionova/Osipova/etc, but she does have some lovely qualities of her own that I'm glad some do appreciate. It signals a bigger problem with management if there is only one person who is able to pick up the slack, which is unfortunate due to the retirements, injuries, and illnesses this season, but Seo herself should not be blamed for this.
As an employee for ABT, she has certainly earned her keep, and I do hope she is compensated accordingly. They are both principals, but by this spring season's end, she will have appeared in 18 performances vs. Vishneva's...3.