Agreed. When you say "all the shiny Apple products you want", you actually mean "the fixed cost of your equipment is irrelevant compared to the value you create in the long run." Say so in plain terms. The most attractive type of equipment benefit I've ever seen on a job posting said the following:

"Pick whatever will make you most productive: we'll order it overnight."

Even if there are one-time integration costs involved in adding a PC user to the team, that candidate may still be more productive in Ubuntu. Trust their judgement.