How is this scored?

A ball that hits the umpire before passing a fielder is declared a dead ball. He made the correct call.

...and its scored interference on the umpire and no AB per 10.02
10.02 says
a) The following records for each batter and runner:
(1) Number of times batted, except that no time at bat shall be charged when a player
(i) hits a sacrifice bunt or sacrifice fly;
(ii) is awarded first base on four called balls;
(iii) is hit by a pitched ball; or
(iv) is awarded first base because of interference or obstruction;

Sorry, but no hit...

Not so fast, there!

10.05 BASE HITS
(a) The official scorer shall credit a batter with a base hit when:
....
(5) a fair ball that has not been touched by a fielder touches a runner or an umpire, unless a runner is called out for having been touched by an Infield Fly, in which case the official scorer shall not score a hit; or
......

Not all interference is equal.

I stand corrected, thanks 3Finger... Still got that darned CI on the brain. I'll die happy if I never hear of that again.

In hindsight, I should've known this. I vaguely remember a legend of the Red Sox back in '41 on the last day of the season if Ted Williams hit a ground ball to first or in the hole, his team mates planned to let the batted ball hit them so he would get credit for the hit and wouldn't lose his .400 season.

He was offered the opportunity to sit on the last day's double header with a .400 even, but elected to play. I think he went 4-6 or something like that and raised his average to .406. None of them were on interference.