The move is almost certainly only a tactical adjustment due to Disney's lawyers appraising the state suit as the more appropriate and favorable forum for state law claims. Generally, federal courts do not like taking up state law claims that are appended to a federal constitutional law claim; and even when a federal court takes up state law claims, they tend to complicate and delay the progress of the case.
In this instance, I believe that Disney's lawyers see the federal judge as more likely to issue a favorable ruling and will do so more quickly if the federal court case is based solely on the First Amendment.
"I meant they didn’t have federal standing."
But after reading your subsequent post on the matter, I see where I erred. A tactical adjustment seems the right explanation.