It isn't hard to parse at all. He has been using the word "hoax" to refer to false narratives and accusations for months if not years. He is clearly pushing back on the criticisms as being false, as being a "hoax".
There is also the fact that his actions don't make any sense at all if it were true that the President thinks the outbreak is a hoax.
Trumps's actions at the time (28 Feb) were things that indicated exactly that he thought coronavirus wasn't a threat and would go away soon:
Because of all we’ve done, the risk to the American people remains very low.... Hopefully, we’re not going to have to spend so much because we really think we’ve done a great job in keeping it down to a minimum. And again, we’ve had tremendous success — tremendous success — beyond what people would have thought.
and
So we’re at the low level. As they get better, we take them off the list, so that we’re going to be pretty soon at only five people. And we could be at just one or two people over the next short period of time. So we’ve had very good luck.
I really think he is using "hoax" as a synonym for "bad" and is referring to coronavirus, criticisms of his response and the Democrats all at the same time.
There is also the fact that his actions don't make any sense at all if it were true that the President thinks the outbreak is a hoax.