Dont tell him that, he will tell you that they wasted the extra money in having the extra people and equipment around simply because they wanted the best.
Pro race teams do check sag, I have personally seen them do it and they have a shelf full of springs to choose from and they have data on every track they go to as a baseline, plus they already know the weight of their rider. A motorcycle from the factory is set for a specific weight and if you are NOT that weight, the spring is wrong for you.. Fact.
Why does Ohlins specifically state a sag measurement if it doesn't matter? Why do the guys I know who have worked on WSBK and AMA teams set sag if they have a new rider on their bikes? Why do they change spring rates on a per track basis? They change the rates because a spring is designed to work through a specific range of travel. This can be tailored to a specific LOAD that is generated (weight) dynamically.. A 125 lb MotoGP guy can generate a ton of load (weight), FAR more than a street rider or AFM level rider can, consequently, they need stiffer springs, because they are generating an appropriate load for that spring rate.
Road bikes only generate a narrow range of load and so we can figure out what that load is and allow for it, by choosing a spring rate that is appropriate for that load, which consists of rider weight and the amount of load that rider generates while riding. A 100 lb rider on a street bike on street tires (even at the track) will not generate the same load as an equivalent rider that weighs 250 lbs, the laws of physics dictate that; unless that 100 lb rider can somehow generate the same load as the 250 lb rider (and they can't if both riders are on the same equipment, same tires and are the same skill level).
Again, if springs don't matter and sag doesn't matter, then why does every single top end manufacturer of suspension specify sag settings and SPECIFICALLY state that you will need a different spring if you can't get that sag correct? Ohlins, K-Tech, Moton, JRZ, Penske Bi-Tubo ALL specify the sag range for their products and tell you to change the springs if you can't reach that figure.
I guess some people are so smart that they know more than Ohlins, Penske, Bi_tubo and actual people that have worked on AMA championship winning teams and set up the bikes.. INCLUDING SAG.... Yes... The guy that set up an AMA champion's suspension set his sag at each racetrack...
Dave Moss (and a few other suspension gurus) goes to every round of the AFM and other championship races and set up the suspension for many of the champions, including Rickey Corey (multiple AFM champion and sometime AMA rider) as well as the last 5 champions.. Guess what? He sets their sag and advises them on spring rates.