We have a factory installed articulating arm mounted on the edge of that cabinet, backed by the framing. Our TV is 6 lbs, and we take down when in transit. That wall can be reinforced, as the other side is the closet/pantry, and could easily handle 9 lbs. The question would be the rigid attachment you mention and any associated bouncing and jarring of the TV itself. I would talk to ETI about your plans and see if they have any suggestions. There is a fair amount of framing on the backside of that wall and they may have some advise.
Steve and Debbie
2016 - 21'
“Get out the map and lay your finger anywhere down” -Indigo Girls