#22 was his father, Todd's, number back in the days when he controlled the Danish league winning seven Danish Championships on his way to becoming the all-time leading topscorer (by far).
Todd was an American coming to Denmark after being very close to making the NHL. I dare say that if there were 32 teams back then he would have been a 1000 games player in the NHL. He was a scoring machine on the level just below NHL and had he cracked the line-up somewhere he would have kept on sailing in the top-2 lines of whatever club for years and years.
But it was harder to get in to the league and the playing style was more rugged back then, so he left for Europe pretty early.
More or less by coincedence he landed in Denmark with Herning and found a girlfriend there so he just stayed put for 14 years as a player and became the coach of the club winning another 3-4 championships that way as well.
A very demanding coach with a heated temper, but very knowledgeable and tactically sound.
My guess is Oliver picked #22 to honour his dad. #22 is the only retired number in Herning as far as I remember. Probably will retire #18 (Daniel Nielsen) soon as well, I would assume, since he retired in the spring being the all-time scoring leader among defensemen in Denmark and the player with most games in the Danish league ever.