For sure. And some of the Cubase users could be using version 5, etc.
I'm not saying the UAD Forum survey is the absolute gospel truth, but it is an indicator of UAD users' favorite DAW's. It's not an endorsement of X2 specifically, but with Sonar in general ranking #4, that's a respectable showing for the brand. (Again, only 4 systems showed up with double-digit per centages; everyone else was lumped below that.)
Those who continually worry on this forum that Roland might abandon Sonar should realize that no company that owns this size of market share would ever discontinue such a product. Also, since Sonar is jam-packed with plug-ins, I would guess that it ranks even better with people who haven't invested in UAD cards and plug-ins.