Managerial opportunism is basically when a person takes takes advantage of a managment position, and tries to get their in any manner that they can. Some examples of this are: job hopping, on the job consumption, and excessive product diversification.

It seems to mean Taking advantage of opportunities, but not of people.

Taking advantage of circumstances, often selfishly, when you are in a certain rank (e.g Lieutenant)

unseemly

Arnaud Banoun has written:

'L'opportunisme' -- subject(s): Opportunism (Psychology)