By definition, the WDC is awarded to the driver who has more points after the last race.
Not most race wins, fastest laps, best overtakes or most poles.
Has always been the case and hopefully always will, unless we adopt Bernie's medal system...
Did Nico drive a brilliant race in Brazil?
Nope.
Was he faster than Lewis?
Nope?
Was he faster than Max?
Hell no.
Is he leading the Championship?
Yes he is.
Can't speak for the man, but I guess that was his only goal going into such a race under tricky conditions.
He only needs to do it once more, and I bet that will also be his only goal at the final race.
No matter what he did or didn't do throughout the year, at the end of the day people could find something bad to say if they wanted to, all that matters is who has the most points at the end.
And just for the record I couldn't care less about which of the two Mercs gets it, I'm a Ferrari fan!

The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents. H.P.Lovecraft