I have no issues with the "Wild Card" rule allowing 1-3 athletes who were not at the competition or even rostered when the bid was "earned/accepted". This could be because on a LAG team with 36 on the floor, this isn't going make/break us, but we have a larger amount of people that could potentially get hurt/sick.
I think, as others have stated, if it was Cheerleader X no one would care and most wouldn't even know about it. I guess what adds dimensions to this situation is that :
1)She is very well known in the cheer world for her talent and the teams she has competed on
2)For the last 3 seasons she has been involved with multiple gyms (some during the same season) which can lend an air of "disloyalty" to the situation
3) As a minor, she decided to try and open her own gym, which did not work out for many reasons
4) Now there is the rumor that she will be returning to one of her past gyms to compete on a team that performed very well the weekend before.
IMO this is an athlete who is probably going to include cheer as a means for her future whether as a gym owner or a coach. Her reputation would be extremely important in obtaining that goal. As others have stated, Lionheart's last performance is not how she wants to be remembered...we ALL would like our last performance to be the pinnacle of our careers in this sport. I'm not rationalizing the situation, but GB's is a little different than the average cheerleader.
I see both sides of this situation and can certainly understand the "side eyeing" of it as well...especially since most of us will never really know all of the details. To the average person, we see a successful/popular cheerleader who has been on numerous teams/gyms decide to open her own gym, have difficulties with new gym, close gym, and within a week is rumored to be on another successful team within 3 weeks of Worlds. If the new team really needed a new flyer, and no one was replaced/removed then I see nothing "ethically" wrong with it. If this is not the case, then I would have some issues with it, but it seems in this sport that as long as gyms aren't "breaking the rules" ethics/morals go right out the window.