They're investigative journos mate, have programmes to make, and need to come up with something which people will watch and talk about.
Programmes about "dodgy" foreigners will appeal to the xenophobes in the country, and if you can tie that in to the most popular and financially successful sport in the country then you'll get a fair amount of interest. The very fact that we're discussing it proves this.
I dare say there's an element of truth in the link between Usmanov and Everton, so I don't blame Panorama for highlighting it. As a programme, Panorama is nowhere near as relevant as it was ( I can't remember when I last watched it tbh ), so, to some extent, they're trying to justify their existence.