It doesn't matter what his friend gives them. I can beat it _and_ for those who prefer just working on technical design and code with an experienced team, I can offer them that. No forced mentorship taking up your time. Since senior engineer mentorship is a different thing, I can easily give them a better job than the "you have to help train junior engineers" guy.

Altogether, this is the best approach. The guys at two years and slightly more of experience have learned on the job from someone else and you can get them for relatively cheap vs. the huge opportunity cost of having your senior engineers mentor people if they don't want to.