No, that is exactly how the English language works - context defines what is said (not pulling out words like "it").That's not how the English language works. Maybe you were hoping that's what he said. He presented two topics and said "it" is a hoax.
1. Either he said the coronavirus is a hoax—which means it's not true.
2. Or the DNC's politicizing the coronavirus is a hoax—which means it's not true.
Trump said that he was starting a COVID taskforce. That proves he did not mean by his words that COVID was a hoax. Trump described the DNC as politicizing COVID (creating a hoax). "It" is what the DNC was giving (the "hoax").
You are putting way too much faith in Trump's linguistic exactness and prowess. I thought it was silly when Clinton did it ("what is is") and I really can't see any benefit in it now.
You seem to be confusing the meanings (or possible meanings) of individual words with actual communication (which not only includes but is dependent upon context).

