They are trying to break states’ legal control over their electors. If they prevail then Trump electors in other states could be freed up (potentially).
They tend to forget this is the United States of America.
The founding fathers wanted to ensure the States retained some control over their destiny, as a counter-balance to the feds overreach. Break state's legal control over their electors, and you break the United States into something else, and that something will be ugly. Little by little, the state's power over their own control is whittled away, further lessening the freedoms that Americans enjoy (or used to enjoy).
The Constitution plainly says that the States select (and therefore control) the electors.
On the other hand, it wouldn't be the first time a federal court (or SCOTUS) has ruled that what's actually in the Constitution, isn't.
Mark