The conversation is recorded? That definitely could do something. I don't know about the laws in Texas, nor specifically for EMTs, but as a CNA I can definitely lose my license for verbal abuse of any nature, including what he did. The fact that there's concrete proof of this, not just a "different point of view", means there would be a solid case against him.

I did a bit of Googling and found this for you: https://www.dshs.texas.gov/emstraumasystems/qihome.shtm

Under the "valid complaints" list there's something that says "Unprofessional conduct which might endanger the public". This situation definitely sounds like such a case to me and is worth bringing up.