Illegal is a strong term here. While the wiki link you included indicates there might be some permitting nuances, I've seen nothing claiming the power is "illegal."

xAI removed its illegal gas turbines and obtained permits for the others only after being sued by the Southern Environmental Law Center. They then built another unpermitted site (Colossus 2) across the state line in Mississippi, and they are being sued again. [0]

"The company began operations at its first site, Colossus 1, in June of 2024 and used as many as 35 unpermitted gas turbines to power the facility. Despite receiving intense public pushback over the use of illegal turbines and the lack of public input and transparency around Colossus 1, xAI officials said it planned on “copying and pasting” its unlawful turbine strategy to power Colossus 2."

"xAI removed its unpermitted turbines at the Colossus 1 data center after SELC, on behalf of the NAACP, sent a notice of intent to sue under the Clean Air Act. The company obtained permits for its remaining 15 turbines."

[0] https://www.selc.org/news/xai-built-an-illegal-power-plant-t...

The ethics are questionable, legal or not. Anthropic are tarnishing their image again here.

Not sure how much it hurts then compared to blocking openclaw though.