It is definitely interesting circumstances. Bowie, at 10 years old when Achara's calf was conceived, certianly was not expected to breed successfully so soon.
As for Kandula's breeding ability, that is interesting as well given that he and Bowie had the same upbringing (AI birth, no mentor bull interactions as a calf). The only difference between them is that Bowie grew up alongside another calf, which could have been a pivotal factor here.
That being said, I don't think we can nessecarily chalk his lack of breeding to behavioral lacking. He may just as easily have a health issue preventing him from producing calves (Low-sperm count, etc) or even simply that the SSP didn't view him as a proper match for the facility's genetics. His move could've been just one of necessity to provide him with a bull mentor with no intention of breeding him there.
It is my hope that the latter is the case, and that we will see him being a canidate for a transfer in a few years when Bowie has matured more and would benefit less from the company of an older bull. If he is capable of breeding, then he likely is being retained on-site to provide socialization for Bowie.