Nothing out of the ordinary. Guy sold 4m shares over a few months (all of which have to be pre-announced 90 days in advance). Still has over 25m shares.
The article says there were no trading plans used, so it's not clear to me whether selling was announced 90 days in advance. Where would I find the announcement?
It's generally considered unwise for executives to sell any shares at all except according to a preannounced 10b5-1 plan, but it's not required and he doesn't seem to have done so here. (You're right, of course, that there a lot of legitimate reasons he might have wanted to diversify 20% of his shares without waiting 90 days.)
They can influence timing of information release; Whether delaying or expediting.
Just pointing out that even with the notice there is still room for shenanigans.