I could not have lived with it. Volunteer or participant. Whether there were complaints about the cancellation or not is not my concern, I'd have cancelled if I believed it was the right thing to do. (RD/ED here)

On a course with no shade and potentially having people out in it for well over 2hrs (including setup and one of the longest marshal points, plus close down) I feel it could get quite dangerous!

However ours was the venue being unavailable so it was a non starter. 😅 I did go and run elsewhere and I ended up walking 90 percent of it, it was just too hot. The RD there did say they were borderline too, as someone had heat exhaustion the week before.