This really does make sense. What they could do with beaches is leave them open, but close the restrooms, showers, sinks, and so on. That's where diseases are spread, not out in the open. That could be another potential problem, but if people want to go to the beach they can deal with that.
The abstract of that study is confusing, but it would be interesting to see his conclusions. He's not clear on what he means by trajectory, but if he's talking about infection rate that's a difficult extrapolation because of the high transmission rate. With such different conditions during and before a lockdown you can't really do that, even one small group can spread infections rapidly. And if he is talking about transmission rates with trajectory, you can't say that strategies may not have saved any lives because transmission and death rates are two completely different things.
It's unsurprising that abstract is all over the place because phenomenology is not a pure scientific study that relies on data, in fact I wouldn't call it a science at all but a philosophical study. It is a hybrid of philosophy and science that relies on first person experience and intuition to supplement data to reach conclusions. Great care must be used in this type of study because results can easily be unintentionally biased.
Keep in mind the guy who authored this is not a doctor, he's a RA III, which usually make under $50K per year.