Not everyone is knocked out instantly as soon as the punch lands so I don't think u can just say its fixed. Can't say for sure it isn't either. Mike Tyson had several fights that people thought were fixed even Hopkins knocking out oscar was questioned. At the end of the day not everyone reacts the same way getting nailed in the face and the brain can do some funny things after impact so its tough to say. Jmm did nail him though with out question not some phantom punch.
with that said it did look kinda funny. I would like to think a legend like JMM wouldn't partake in something like that. It's not like Ramos is a very good fighter, he's basically a journeyman. But Ramos did lift his chin up while throwing a reaching jab and get nailed perfectly on the chin, which obviously is going to do damage.