I don't think anyone is sure what caused this. So far, people are saying it was a "blowout" of oil and gas. If that's the case, I don't see what a SWAT team would do.
Now, if it were Mexican or Venezuelan terrorists, I could see some value in the SWAT team. However, if we had definitive proof, there would be a big diplomatic storm going on right now.
I am wondering if it wasn't some radical environmental group gone horribly awry in an early Earth Day celebration... They'd want to suppress any info about domestic terrorists while they investigate. At the same time, SWAT would be appropriate for guarding other rigs.