Well you have to look at it from their point of view. If we assume they want to reduce the amount of shares, and we also assume they want to do this in a reasonable amount of time, buying shares on the open market might not be fast enough (as they are limited to quantity they can buy over a certain period of time).
To speed things up they can offer a deal like this, although it would cost them more. Either way, after talking to them, they feel the price is undervalued, so if they can reduce the float one way or another, they might feel both avenues are "cheap" for them.
Who knows!
