The state law is clear, in PA, the deadline to receive ballots is 8 PM on election day. Any vote received after this deadline is not a legal vote, and as such should not count. The term "fraudulent" may or may not be appropriate, however, these are not votes that should be counted.
Before the election, the PA Supreme Court ruled 4-3 that "Ballots are to be treated as timely if they are postmarked on or before election day and are received within three days thereafter."
GOP asked SCOTUS to reverse it.
SCOTUS chose not to reverse it, but ordered that the ballots accepted after election day be segregated in case they ended up hearing the case after the election.
The votes should be treated as valid until a judge rules them as invalid.
Pretty sure it would actually be a crime if they just didn't accept them - can't just do what you want because you don't like how the judicial system handled it.