I attended a state sponsored rules clinic this weekend.
The clinician stated the following:
If a player's jersey becomes saturated with blood and it
cannot be cleaned up enough for the officials to allow him
to continue playing, the coach can exchange the player's
jersey with one from a "bench warmer" who the coach had no
intention of playing in the game.
The officials should instruct the scorer to change the player's number in the book.

I qustioned whether this should be a technical foul since
Rule 3.2.2c would seem to require it.
The clinician stated this is NOT a technical foul.

I cannot find support for his position. Any comments.

Your clinician's answer is correct. He's directly quoting casebook play 3.3.6SitA on this one.

NFHS Casebook Play 3.2.2 Situation E(b): Team A properly submits its team member list and designates the five starters as required at leat ten minutes before the scheduled start of the game. Anytime thereafter, either before the game starts or during hte game the coach asks the scorer to change a number in the scorebook because a player's shirt has excessive blood on it. RULING: The shirt is changed and the number change made in the scorebook without any penalty.

Jurassic Referee, I had not gone far enough in the Casebook, but I knew there was a play in it that was exactly like the original play in this thread. 3.2.2 Sit.
E(b) backs up your Casebook play. The real important part of the Casebook play that you sighted is the editorial Comment emphasing the spirit and intent of the rule.