instead of worrying, try this...
get or borrow a machinist protractor.
measure the actual working angle of the head tube of the bike, no sag.
now measure with sag.
now measure with sag,, and the tire deflated to simulate a shorter fork than what you feel is the "optimum replacement fork length."

report the nearly imperceptible angle changes.

the thing your mate will notice is the loss of two to three pounds (10% of bike weight) from the front of the bike, and the way the bike is easier to pedal up hills since the bouncy fork is now being recycled into Hyundai sheet metal, and the pedaling force is now propelling the bike forward, instead of being dissipated by the approximately 5.5lb bouncy fork.

any bike with a head tube angle between 69 and 67 degrees is considered "slack"
most MTBs show a 67*. angle with no sag.
wild eyed DH bikes may even show a more slack figure.
lightweight road bikes show a 70*+ angle, some as steep as 73 degrees.
most Gravel bikes have angles in the 69* range.

the taller the frame size, the steeper the angle becomes, too.
this is evident on any frame size spec. chart.