They declined to do an expediated hearing, which is what the Republicans wanted. The didn't throw it out, however. What they did was the legal equivalent of 'come back later, we ain't rushing shit.'
According to the US Constitution, state legislations are the ones who decide rules for elections. PA court didn't rule something unconstitutional, they just rewrote the whole thing because of a natural disaster. You think republican judges aren't going to be giddy to rule against the Democrats under the guise of muh originalism?