The terminology is perhaps not exactly correct because the "grids" one would expect Texas to cooperate with are either the Eastern or the Western - but it does make a fair degree of sense. It's pretty open that Texas's reason for operating their own interconnection is to avoid federal regulation by the Federal Energy Regulatory Commission. By operating an electrical interconnect that is mostly confined by the Texas state borders, they create a strong argument that there is no interstate commerce, thus avoiding any federal oversight.

Renewable energy construction is proceeding rapidly in Texas because events have shown that the Texas interconnect lacks sufficient capacity or interconnection to reliably meet Texas's electrical demand. There is definitely a climate advantage, but it's important to understand that renewables are increasingly the cheapest option in the southwestern United States where land (the main resource wind and solar consume) is inexpensive, insolation is high, and the landscape is often amenable to wind production. The problem remains acute and the Texas legislature recently approved a ten-plus billion dollar program to construct new gas power plants to help address the need. It's more of an all-out scramble than a climate change strategy.

This situation is mostly self-made. Texas has not been a very attractive market to build generation in because the lack of interconnection makes it difficult to achieve good utilization over the full year. Texas has repeatedly backed out of efforts that would improve connectivity between Texas and the Eastern and Western through rectifier-inverter systems, for example the Tres Amigas Superstation, largely over political concerns about interstate commerce. The Texas power crisis is long brewing but didn't really achieve political visibility until the last few years.