Nonsense. There's plenty of evidence to suggest that it wasn't the canon Mayday [The Unlimited game, the fact there is canonically more than one Mayday with a similar timeline, Peter's leg etc]
Slott is a known liar, he says anything to get a reaction out of fans. I'll go with what Tom and Ron hinted at, the real Mayday is still out there and unaffected.
It's only defeatists that claim otherwise. Don't be one of those.
I don't have the issues in front of me, but can you tell me more about the differences between the Spider-Verse Mayday and the previous MC-2 Mayday?