to be x: adjective of someone is very idiomatic in English.
Situations:
Person One: John wants to win the race this year! [John is a slow runner]
Person Two: That's very ambitious of him.
Person One: He only wanted the credentials.
Person Two: That's very cynical of him.
Person One: They want to give us a party!
Person Two: That's very nice of them.
This form is common and found everywhere in English.
[Please note: the paragraph has a couple of odd things. Generally, for example, we say practice law, no the. And we would not say: practice corporate business, which the sentence implies. It just isn't the best writing....]
That sounds too cynical for him. means: Those comments or ideas sound to cynical for him to make or have, respectively.