Here's another simple point...
If they want to go with Proteus more than likely they would put his age around 20 years old, give or take. They could go with a younger kid, but what is most likely is a 19 or 20 year old.
For example, IF (and it's a big if) Hardy is Proteus, then he would have to be around this age.
That means that Moira got pregnant right around the time or the events of First Class (in 1962 or 1963).
There would be two main options for this to be a possibility...
1. She was with CHarles (or someone else) during the events of First Class (Charles would be the only logical option).
or 2. She got busy not too long after the events of First Class. This seems unlikely. Her mental state at the end of First CLass didn't seem to be one ready to have a relationship that would lead to a child.
Maybe Proteus won't be in the movie, but again I just don't see why it would be worth including Moira (Rose), other than the fact that she's hot!
