TexasCHLforum.com

It's a very liberal interpation of the bolded text.

Section 30.06
(f) It is a defense to prosecution under this section that
the license holder is volunteer emergency services personnel, as
defined by Section 46.01.

Section 46.01.
(18) "Volunteer emergency services personnel"
includes a volunteer firefighter, an emergency medical services
volunteer as defined by Section 773.003, Health and Safety Code,
and any individual who, as a volunteer, provides services for the
benefit of the general public during emergency situations. The
term does not include a peace officer or reserve law enforcement
officer, as those terms are defined by Section 1701.001,
Occupations Code, who is performing law enforcement duties.

I'm guessing he's misapplying the new volunteer first responder law.

Neither are ACoE. They're private.

Actually both lakes were created when CPS Energy built the power stations and dams. They manage the lakes and dams. Management of the park is contacted out.

https://en.wikipedia.org/wiki/Victor_Braunig_Lake