On the subject of "rude" ASIC inspectors, usually they will formally identify themselves and explain what they are doing. The fact that they are now showing a bit more presence to enforce ASIC display requirements has come about because GA's attitude is well known thanks largely to these pages. Argue the toss all you like but you will be on a hiding to nowhere.
In essence a yellow line would have been needed to denote the airside security zone, anyone without an ASIC stay out.
Actually it is usually a blue line that is used to delineate secure areas under a TSP at an airport so as not to confuse any taxi or parking limit lines.
The introduction of screening for RPT aircraft > 20,000kg was orginally published in the white paper as taking affect from 2014, however Mr exploding underpants was a catalyst for the government to bring that fwd to 01 Jul 2012. Many airports will be out of pocket initially but not unlike the introduction of CBS to the 26 jet RPT serviced regional airports that was announced in early 2007 and implemented by Nov 2008. Airports being serviced only by Rex will escape the screening requirement with the Saab falling below the 20tonne threshold. However where they share an apron within the operational period of a larger screened aircraft, they too will have to be screened.
Binghi, The OTS is looking at a classification scheme for screening and other security requirements. Not sure if the ASIC display will be one of those requirements relaxed or changed although it would make sense.