What is the opposite of opportunistic?

Opportunistic is defined as:

Taking immediate advantage, often unethically, of any circumstance of possible benefit.

(http:/www.thefreedictionary.com/opportunistic)

If we take the direct opposite of it, it will be:

"inexpedient"

(http:/www.opposite-Word.com/o/opportunistic)

which is defined as:

not suitable, advisable, or judicious

(http:/www.thefreedictionary.com/inexpedient)

I think this pair of Words doesn't really show the opposite meaning.

My opinion is, if we see 'opportunistic' as self-centered behavior of someone, which then displace this Word closer to

'egoistic' : One devoted to one's own interests and advancement; an egocentric person.

(http:/www.thefreedictionary.com/egoistic)

maybe the most suitable opposite Word of it would be:

altruistic(http:/www.opposite-Word.com/default.asp)

which is: (altruism) Unselfish concern for the welfare of others; selflessness.

(http:/www.thefreedictionary.com/altruistic)