The idea that you've put forward that Covid 19 is the reason less people have caught flu and not because of social distancing and mask wearing, seems to me to be at odds with the article you've posted a link to though.
It mentions that the first person outside of China to die of Covid also had flu, many of the people in Wuhan who had Covid also had flu, that there is concern that children returning to school catching cold and flu viruses may cause problems for people who develop covid and make it harder from them to recover. All of which show the two viruses can obviously coexist.
It does mention that there is some historical evidence that one virus may at times stop another taking hold, but it absolutely does not say that the reason flu infections are down is due to Covid, rather than social distancing or mask wearing. To be frank I think its irresponsible to say that it does, or to suggest its viroligist 1-0-1 that this is definitely the case.