14 years old, no, I think not. 16, that is a bit more reasonable in my opinion.
I think all of these journeys should be measured at least against past journeys, and that means there are probably going to be life threatening trials. I don't know if Zac Sutherland ran into any real danger, I didn't follow his circumnavigation that closely, but Tania Aebi did, and so did Donna Lange, and a whole host of other solo circumnavigators back to Joshua Slocum, many attempts ending in death. Most of the solo circumnavigation attempts involved severe weather at one point in the journey (at the very least), are these 16 year old kids ready for that ? Is a 14 year old ready for that ? I'm not sure I'd be ready for it, so I wonder.
And now it looks like there is a third young lady tossing her hat into the ring, Zac Sutherland's sister Abby Sutherland, link provided.
Source:
Younger sister of Zak Sutherland eyes non-stop trip around the world