I can't speak with direct experience as to what the API allows - geniuses like the author of this script could answer definitively. However I have picked up a little about the way the scripts work and I like to think I know a bit about computing in general.
I would be, frankly, amazed if the WME API allows you to change the creator. The API is there to allow WME to work - and creating segments under another editor identity is simply not something that WME does. If it was
possible, the potential for mischief would be high. I have no doubt that creator is not an attribute that can be specified when creating a segment - it will be set by the server based on the logged in user asking for the segment to be created.
AFAIK the scripts only have access to objects and attributes that are available in the editor anyway. For example, note how average segment speed has recently become unavailable because it's been removed as an available segment attribute. In the same way, the scripts can only perform actions that can already be performed by editors. Although some scripts may seem to perform incredibly complex actions, they're just doing what computers are supposed to be good at doing - automating things that take too much time to do ourselves.