If Apple's truly deviously smart, they'll promote some idiot through the retail ranks then hype the heck out of them informally through backroom channels to float the lure before Microsoft. Then let Microsoft persuade the said idiot to join their staff... 
All kidding aside, not sure I see what the big deal is. It's just business as usual and what smart companies with money do: try to leverage their presence by hiring talent with a proven track record from competitors.
Why do people leave a job? Money, lack of a sex life (at some places due to the work hours and days), boredom, issues with colleagues or management, lack of promotion or responsibilities, spouse wants to relocate, new family and needing time with them, substance abuse, fraud or theft, and 101 other things that could compel someone to leave. So what? Let whomever leave... leave, and let those who's still at Apple in continuing the tradition of success.
All kidding aside, not sure I see what the big deal is. It's just business as usual and what smart companies with money do: try to leverage their presence by hiring talent with a proven track record from competitors.
Why do people leave a job? Money, lack of a sex life (at some places due to the work hours and days), boredom, issues with colleagues or management, lack of promotion or responsibilities, spouse wants to relocate, new family and needing time with them, substance abuse, fraud or theft, and 101 other things that could compel someone to leave. So what? Let whomever leave... leave, and let those who's still at Apple in continuing the tradition of success.