We had a similar call go against us at Boilermaker. Didn't like it, either -- but it was the right call.
Our student operator on the field asked the head ref about the call right after the match, and pointed out that had the tube been removed the robots would not have changed height. However, as the Q&A response cited above makes clear, "supported" is not interpreted by such a test -- it is implied by contact of a gamepiece under the ramp-bot, and a robot supported by a supported robot is also supported.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)