Intentionally driving on top of another robot could be considered a violation of <G9> (either as intentional destruction or entanglement of another robot) and the team may be disqualified based on the severity of the infraction.
The Q&A you referenced is an answer to whether pinning can occur during Autonomous mode. We have clarified our answer to that question.
If you are pushing a robot down into the foam surface, this would be considered pinning a robot against a field element (the floor in this case being the field element). Even if you are not moving, your robot would still be pinning the opposing robot.
Much of this depends on the interpretation of the head referee at your event. He/She would need to judge the severity of the infraction and make a ruling.