Alone it probably would not have done it, but the sanity of Group B (or lack thereof) had been in question for a while: earlier in the same season Joaquim Santos lost control of his car after avoiding a group of spectators (who'd routinely play chicken with cars) resulting in 3 deaths and 30 injuries.
And the previous season Bettega had died on the same course Toivonen and Cresto lost their lives on, and Vatanen was gravely injured in Argentina.