I think those reasons aren't too good..
If someone goes to all the trouble of signing up to be part of the team, they obviously aren't immature, quiting, lazy little....
The reasons (Mainly ones like "Failing to deliver the required workload, due to real life commitments", and "Finding out that working for OFPEC wasn't the 'glamorous' job they thought it was"), can easily apply to people over 18. And "Failing to deliver the required workload, due to lack of interest" too, that could quite easily apply to a 86 year old, couldn't it..
I think maybe a better rule would be "Applicants must active in community, and have some knoledge of scripting and mission making", or similar
Thats my thoughts..
And to prove it, what age do you think I am?