I’m not a lawyer and not good at reading legalese. Did Texas argue that these states did not follow their own laws, which with the mass of evidence shows the elections in their states were rigged and disenfranchised Texas voters, or did they go for more nuanced points of law?
They were right and the law was on their side.
The Supreme Court could have accepted it and ruled in Texas favor as a matter of law.
The Supreme Court carefully selects cases based not just on their merit, but on worthy they are shaping the law and setting precedent.
A very reasonable interpreting rationale was that, for at least some of the Justices, the Texas suit did not contain the case law, policy position and public perception that they wished to adjudicate to resolve the issue.