Explain the apparent irony in the fact that Odysseus worries about meeting som savage who would be of great strength, and would respect not right the law.

I would think that Oedipus himself rarely obeys the laws of the land he is in. One can question Oedipus's breaking of customs and laws so easily. His blinding of the Cyclopes on his own island is a case in point. Oedipus steals food and blinds Polyphemus on an island that he (Oedipus) is a guest in.