The problem here is that the man probably (he doesn't actually say that) owns the plane already.
If he doesn't own the plane at all, then the company could rent one in, free issue it to the chap, pay for everything, and provided he is not contractually required to fly then he could just fly the whole lot of them to the meeting. Zero cost to him.
If he already owns the plane personally, we have the grey area. I think it's right that in his cost recovery he's limited to the PPL cost sharing formula. This in turn leads us to the old chestnut of what comprises direct costs, which the CAA has quite deliberately never defined openly.
If he already owns the plane either wholly or partly but via a limited company, then that company can rent the plane to the man's employer and IMHO we are back to the first scenario.