Because the offence exists, the driver would be charged with causing death by careless driving (or, quite possibly, dangerous driving - you'd need an expert to decide which one the right charge is). There is no equivalent offence for cylists, and the jury decided that manslaughter wasn't the right conviction for Alliston, so the only charge available was the one he got dinged for.
For causing death by careless driving, the sentencing guidelines are:
View attachment 374069
So if we pretend that Alliston was a driver, not a cyclist, what does this tell us? I think we can agree that Alliston's behaviour fell not far short of dangerous "driving" (he knew by calling out that he was in danger of hitting the victim and he didn't even slow down), and there are two aggravating factors:
1. Other offences - a bike which was wasn't road-legal
5. Irresponsible behaviour - he falsely claimed that the victim was responsible.
So I suspect the sentence wouldn't have been all that different. But you really need a sentencing expert to tell you.