I think is an open question

if the media is straight lying about him being able to swim at all, that might be a red herring.

From the twitter thread the guy shows a screenshot and the screenshot DOES NOT CLAIM he couldn't swim. https://twitter.com/OliLondonTV/status/1683629201792933888/photo/1

it's a quote from the State Police statement.

a male paddleboarder who had gone into the water, appeared to briefly struggle and did not resurface.

They are not claiming he couldn't swim. And this is a police statement which often are unusually formal. This is just what a witness observed.

The twitter poster then makes this massive jump to a conclusion.

“Appeared to briefly struggle and did not resurface.” - this would indicate he could not swim and was unable to stay afloat.

No it doesn't. There's lot of other things that could have happened here as you point out.