Andrijander,
I think you are confused in what PPrune Radar said because of the way the English language works. He was trying to get across the fact that the incident of the A/C 'almost landing on top of another' could actually have been an result of a perfectly legal clearance (a conditional clearance)... this allows the pilot to continue that little bit longer on the approach, which may make a bystander think that an airmiss (airprox) has just occurred.
In the second instance he is saying you can sit on your backside (not you personally) and whinge about things all day long, blaming everyone else, the system etc; or, more productively, you can highlight perceived problems and, if needed, get them fixed (hopefully)