Yes, a holistic education can prepare students for life after graduation, because it is important that students learn about all parts of life, rather than just book learning. Students need to learn more than just English and Math. They need a well-rounded education because they need to know how to function in society, not just at a job.
Teaching humanity is not a new way of thinking. Many generations of people have taught their children to be kind, peaceful and to take care of others. Why would this way of thinking hinder anyone after graduation? If anything, providing a holistic education helps students to learn to foster their relationships and thrive.
Well, that's sort of the point isn't it? Holistic means "as a whole" so an education that claims to be holistic would (or at least should) be able to prepare students for the real world, or as the asker put it "life after graduation." But there's such thing as being entirely prepared. There's only so much you can do without the benefit of real world experience.
I'm not much of a holistic believer but I do believe that a holistic education can help lead to a balanced education and truly prepare students for the world outside of their schools doors. Id on't think it is such a crazy thing and would support it for that reason.
Yes, a holistic education can prepare students for life after graduation, because it can help a student deal with all aspects of life. A student who only knows one thing will be very good at their job, but might not be able to understand current events, or how to fix their car. A well-rounded, holistic education is best.