I agree. However, from the article:
“Gay Rights Attorney John Nechman says there really isn’t any legal recourse for Dewberry and his partner to take.
‘We don’t have protections in most parts of Texas for Gay and Lesbian people, other than in Dallas, Austin, San Antonio and El Paso,’ says Nechman. ‘There’s really no protections to go after someone because they’ve made a slur. Now if they made a slanderous statement, a libelous statement, where they claimed for example that the two were committing an act that they didn’t do, there would be legal action to take against them.’
You mean, possibly, that the claim of the waitress calling them "fags" may backfire if the waitress didn't really call them "fags"?