Not a supporter of Real Madrid or "The Chosen One", but consider this an intelligent tactic. I guess it comes down to your personal definition of unsportsmanlike conduct. Not only does it not go against the rules, I can't see how it violates the spirit of the rule.
Every manager will try to acquire an advantage. If that can be achieved for your team without directly harming another team, it should be applauded for its effectiveness. The outcome of the Ajax game was not changed, the cards were not given for putting other players' health in jeopardy and the desired result was achieved.
I can't help but think, none of this would be discussed so passsionately if the controversial Jose Mourinho wasn't involved. He does have a disgustingly high opinion of himself, but I don't see why that should be used attempting to prove an unsportsmanlike accusation. I think Jose is good for the sport, and popularity driven competition results should be confined to American Idol or Dancing with the Stars.
UEFA wanting to conduct an investigation reminds of two children playing a game; one child does something unexpected and unconventional which causes the other child to scream, "That's not fair!"