Found another and cheaper (interim) solution to removing pin 13 from an HDMI cable or getting the specific Lindy non-CEC adaptor (which I found rather expensive).
This was detailed on another Android media player forum I found.... (can't recall which one).
It is to buy two very cheap HDMI/DVI adaptors (specifically HDMI Male plug to DVI Female socket + DVI Male plug to HDMI Female socket) and screw the two DVI ends into each other. This gives a single HDMI male to HDMI female unit that can be plugged into the HiMedia and to the standard cable.
DVI standard has no CEC so there is no transmission or interference anymore.
My ARC from TV to AVR now works as it did before