I don't think Engine Yard has abandoned support. Back in April they added funding for a Rubinius developer [1]. But they did lay/move off the full-time Rubinius team, back in 2008-2009, which, as far as I know, was due to financial constraints [2] [3], not a lack of interest.

[1] https://blog.engineyard.com/2013/engine-yard-expands-support...

[2] http://blog.fallingsnow.net/2008/11/18/a-sad-day/

[3] https://news.ycombinator.com/item?id=424000