I pretty much agree with the sequence of actions needed in order to prove an existence of a virus that you outlined in the quoted note, the only thing is that one has to actually perform proper experiments to prove that the particle they isolated is indeed pathogenic. However, in the paper where they presented Wuhan HU-1 "isolate" it clearly states that no isolation/purification was conducted, they just sequenced patients fluids which always contain thousands of different particles including cell waste. Moreover, they did not prove that whatever they had in their sample was pathogenic.
"To investigate the possible aetiological agents associated with this disease, we collected bronchoalveolar lavage fluid (BALF) and performed deep meta-transcriptomic sequencing. Total RNA was extracted from 200 μl of BALF and a meta-transcriptomic library was constructed."
They just ran a computer program on RNA they got from a "soup" of particles and virtually generated a lot of sequences which they then compared to other sequences from their database (which most certainly were generated in the same extremely questionable manner).