This "professor" of ethics (I've never heard of him) advocates coercing young people into giving up two years of their lives. Why just young people? Why not middle-aged ethics professors? Why not the children of middle-aged ethics professors? Why not the children of progressive middle-aged ethics professors, since these are the people who come up with such lame-brained proposals? Sometimes I wonder whether progressives notice the morally relevant distinction between doing something voluntarily and being coerced into doing it. They seem to think that if coercion is what it takes to bring about a good end (by their lights), then coercion is justified. The end justifies the means! How would the mandatory service be enforced, anyway? Would young people who resist be imprisoned? They can't very well be fined, for not many of them are likely to have money. Maybe they would be forced to do community service as punishment, with imprisonment for those who resist. Notice the similarity between this form of punishment and the mandatory service itself.
Addendum: The "professor" in question doesn't even have training in philosophy! His Ph.D. degree is in "Journalism/Environmental Sciences."