Attended a seminar recently, and saw this guy holding the DSLR like that and taking photos of the participants.
1) It's indoor, so the shutter speed is likely to be low. Every bit of stability helps, even though the camera has in-built stabilisation. Holding such a large weight so far away from the body can't be steady at all.
2) I think he looks a bit silly holding a DSLR like that.
Anyway, I saw him reviewing the photos on LCD and frowning, so I presume they weren't too sharp.