To be fair to Norris, he is 44 points ahead of Piastri and beaten him 10 out of 16 races even with a DNF caused by Max.
I mean just last week he totally dominated in Zandavort and Piastri was miles off his pace.
Sure, he has weak starts. A lot of it think comes from being a little pragmatic in terms of avoiding a turn 1 retirement. However it's clear that Norris is faster than Piastri more often than not at the moment.
If I was McLaren I'd absolutely be prioritising Norris for the rest of the season, and would have done so from a fair few races back.