What? No, not at all. That’s a technique that’s taught at the most basic levels of even open water diving. It might be not as ideal if you’re near maximum depths for a general air mix where you might start to run into nitrogen saturation (say longer than 10 mins) at 100+ ft depth, but in the article they were down what seems like no deeper than 15 ft. You could pretty much stay down all day that shallow.

It’s standard training, at least with my NAUI knowledge to practice rescue breathing with another divers spider. My instructor added a few curveballs in that he’d mess up my tank, make me take it off and fix it while without a mask with my eyes closed and breathing off a fellow student’s tank. Nothing to it.

Edit: ok I see you mean as the reporter ostensibly not having any dive training, yeah, probably a bit inadvisable, but they dove with someone with experience and only at shallow depths, the danger is probably a bit overblown after a short amount of instruction. You’re not gonna get bent at 15 ft.