I think they're nice photos. They're crisp and have interesting lighting and shadows.
I don't know anything about this particular photographer, but it's become pretty customary to use some "slider" adjustments in editing software like Lightroom to manipulate exposure, shadows, highlights, sharpness, saturation, etc. after the fact. From there, folks can do other, more "involved" edits like layering, HDR processing, etc. In a lot of ways, the edits folks do with software now aren't that different from what skilled photographers in the past would sometimes do through the use of various filters, lenses or in the darkroom when exposing the film and creating prints.
Also just wanted to clarify it is actually possible to create an HDR-like photo with a single exposure. You would first make additional copies of the original image and then overexpose some at different stops and underexpose others at different stops. You could then import all of the differently exposed versions of the original into your HDR software and go through the normal steps from there.
More interesting to me is the likelihood that these photos are not of giant, powerful waves but instead of small shorebreak waves, maybe only a foot or two high. Here's a couple (albeit not very spectacular) examples of similar shorebreak waves I shot one evening while walking my dog.
I really like Clark Little's wave photos. He lives on Oahu and places himself in the midst of the shorebreak to get incredible "in the tube" photos over dry sand. Takes some skill and some nerve to sit tight in the midst of all this.