Cancelling this would be a sensible idea- not only is the hajj one of the larger mass population movements that the world sees (that list is toped by Lunar new year, as we unfortunately saw earlier this year). It’s also uniquely international in its reach, and connects people to some of the most vulnerable to disease outbreaks. As I said a while ago, before coronavirus emerged:
In addition, it’s also a political risk, as a key factor in the perceived legitimacy of the Saudi monarchy is their ability to be a “good custodian of the two holy sanctuaries”. If the Saudi authorities cannot keep pilgrims to Mecca and Medina safe and well, they will be seen as unfit to rule.