I disagree, and would have no fear of a rule 11 issue by signing my name to the complaint.
The only possible competitor here is the celebrity.
I am not seeing any legal action available. It would be next to impossible to win a lawsuit against the celebrity, challenging the authenticity of the celebrity's autograph when the celebrity says it is not authentic.
FlyingRon, the link to the lawsuit was to show the parties involved and not for that particular anti-SLAPP decision. The class actions are
Todd Mueller, et al, v Collectors Universe Inc, et al, Case No.8:15-cv-0116; and
Nelson Deedle, et al, v Collectors Universe Inc, et al, Case No. 2:15-cv-0528, US District Court for the Central District of California.
But the issues that led to the suits do not apply here. Here you have eBay telling AutographSeller he can't sell the autograph on their site even though the eBay authenticators have authenticated the autograph.
eBay has the right to deny sellers from selling anything. The authenticators did not prevent the sale by saying the autograph was not authentic. The celebrity did that.
All perfectly legal.
Again, AutographSeller's only recourse that I see is to sell the autograph elsewhere, perhaps with the eBay authentication and perhaps with the caveat that the celebrity denies the autograph's legitimacy.
As mentioned before, it is a problem buying memorabilia with just an authenticator's certificate of authenticity. Authenticators can get it wrong. It appears as if they might have gotten it wrong here.