Here's my thoughts on this topic. Wild canids are very versatile hunters, I would imagine they use all their senses in a fairly balanced way. Sight hounds, and scent hounds have been "shaped" over thousands of years to use one sense more than they other, depending on what the humans shaping the dogs needed and wanted. Basenjis have not been shaped in that way. If there were selective breeding pressures on native basenjis they were surely more directed at effective hunters…and effective hunters in jungle and scrub would use scent, sight, and auditory senses equally.
IMO, sighthound doesn't mean anything about body type (expcept for perhaps the shape of the head, and placement of eyes); or whether a dog can see BETTER than other dogs...it simply means they hunt with their eyes INSTEAD of their nose...and vice versa for scenthounds. Basenjis can do it all! And I guess the argument stems from Lure Coursing? Where folks in other breeds were resistant to allowing Basenjis to compete, because they aren't true sighthounds? But really...there is no sport that demonstrates Basenji natural skills better..so regardless of whether they ARE true sighthounds, it is still appropriate for them to compete in lure coursing, as it does test the some of the same skills they would use hunting in their native state.