The take I've been seeing is that Texas lacks standing because they haven't technically suffered injury yet. Once the illegitimate electors are sent to congress then their electors are diluted, aka the injury. Currently the state legislature still has the power to chose Trump electors according to the US constitution. The assumption is they won't because their respective state constitutions say the must send electors for the candidate who won the popular vote. Once they do this against their will only then will the states have violated the US constitution causing injury to Texas