SCOTUS is focused on the Texas complaint. It is the better case with more options for remedy. Constitution is a contract between the 50 states. States have standing, and Supreme Court is the Court of original jurisdiction for such a case.
The Texas complaint is also a landmark case based on precedent of Gore vs Bush. This SCOTUS is made of a majority of Justices who hold the concept of precedent in very high regard.
SCOTUS may hear the other cases on their merits later, but the Texas cases is better and has priority. The fact that the offending states have been ordered to respond by December 10th, 3pm seems to indicate the majority opinion of the Court is favorable to the Texas legal arguments. If that were not true, it would have been much easier for the Court to refuse to docket the case.