This guy definitely isnt a moron. And being the chair of the SEC in the US, hes fully aware of what Bitcoin is and how crypto works in general. He knows its a currency, but what hes emphasizing in his opinion is that he doesnt see Bitcoin becoming a legal currency in the future, like in El Salvador, where its already considered legal tender.
Genslers main concern is how US laws apply to Bitcoin, and his statements likely reflect how he thinks the country will treat it. As Ive mentioned before, the debate here is about the difference between Bitcoin being considered property (as its currently classified in the US) and being a legal currency, which is what hes referring to.
I don't think he's talking about taxation at all (which is the only thing tangible about the distinction if "property" here). He is talking about a currency in the sense of it being a mainstream means of payment, e.g. like credit cards, PayPal, and so on. In that context he is absolutely right: Bitcoin was never designed to do that, and is architecturally prohibited from doing so.
In El Salvador, they specifically changed the tax code there to exempt Bitcoin gains from their capital gains tax. They could do that in the US as well, but it would be absurdly unfair to all of the other things people could invest in, e.g. real estate, stocks, small businesses, farms, and so on.
Here in the US, people have been debating the capital gains tax for decades, with many arguing we should get rid of it. That debate will continue, and perhaps someday they will abolish this tax. But there's absolutely
zero chance they will pick one investment instrument out of the thousands there are to be tax exempt and everybody else has to pay taxes. That will never fly, politically.
(The only exception I can think of is Trump making his own coin tax exempt so it kills Bitcoin and every other crypto and makes him a trillionaire

).