I'm no expert in these things, but here's my understanding. AFAIK, it's up to copyright assignment for re-licensing. For example, contributing to Prometheus a

I'm no expert in these things, but here's my understanding. AFAIK, it's up to copyright assignment for re-licensing. For example, contributing to Prometheus assigns all copyright to "The Prometheus Authors". The DCO just attests that it's OK to do this. So, I don't think there's anything for or against re-licensing in DCO, it's just out of scope.