If you look at the log, the bard was EXTREMELY lucky because the two paladins missed at least 2 strikes of faith in a row when the bard has <200 hp.
If you put in the asepct with location and the "healer", technically anyone fighting a rager can be considered as ganking the rager since the rager doesn't have access to those healers.
"Clearly the gank was warranted." While I agree bards are OP in almost every sense of the way, as I stated above, the bard was extremely lucky. It was plainly a 3 on 1 gank, where the bard was decently skilled and pretty damned lucky, that won him the day. Personally, I wouldn't have any qualms on full looting both of them.
A good showing by the imperial, in both luck and skill, and a poor showing by the goods, in gankiness.