There is no excuse for not using the CTAF just because you are in a jet on an IFR flight plan does not mean you don't have to bother with the uncontrolled radio skills you were taught as a student pilot.
And I don't buy this "I looked at the TACS" excuse. The TCAS would not show an airplane that is on the ground or an airplane that didn't have a mode C transponder on. Also, if the pilot really did take a moment to "look" at the TCAS display that means that the pilot realized that traffic was a threat to safety but decided NOT to use the CTAF frequency.