That is certainly a possibility. The Romans did make certain allowances for Jews. For instance, unlike other subjected peoples, Jews weren't obligated to sacrifice to the Roman gods. So it may be at times the Roman rulers of Judaea deferred to Jewish burial customs, even for victims of crucifixion (apparently they did not do so during wartime). I've never read Crossan's magnum opus so am not sure why he adopted such a pessimistic view.

One problem with the other bones in the ossuary is that they may not have belonged to poor Yehohanan. The forensic analyst who assessed the damage concluded that the bones were broken after death.