Deploying a coronavirus to immunize against covid is a vaccine by definition and deciding to not call it a vaccine as a matter of syntax doesn't make the ADE risk go away
vaccines against COVID have already been developed. They already exist. Designing them took a couple of weeks. What takes time is testing them to make sure they are safe and effective. The cold causing coronaviruses would also have to be tested for safety and efficacy in an application of preventing COVID-19. That's what the bulk of "developing" a COVID vaccine means in our modern context - testing through clinical trials. The first RNA vaccine against COVID "existed" a week after SARS-COV-2 was sequenced, and vaccines that use parts of the virus itself "existed" basically immediately after SARS-COV-2 started existing. Using the cold virus is actually a harder problem scientifically since you're using a different strain of virus to protect against SARS-COV-2 epitopes - the mechanism and safety profile is harder to predict and evaluate.
Of course we don't yet know how effective it is. But how don't we know its safety profile? Why should a cold virus be more dangerous just because we use it as a vaccine, especially if we spread it the "usual" way as opposed to injecting it?
