I'd say do it. Once you start sailing and see what is involved you will be able to more accurately gauge whats involved in sailing around the world.
I'd suggest reading all the blog posts, in the following link. It shows pretty much what to expect and different eventualities you need to prepare for, keep in mind that he is a seasoned sailor, and has people with the skills and contacts to get him help when he needs it.
Solo Around the America's Under Sail | An audacious attempt at sailing the Northwest Passage and circumnavigating entirety of both continents, to benefit Chesapeake Region Accessible Boating
Remember as well he is doing it non-stop, if you stop here in there you'll be able to fix things he isn't able to.