Not sure why you think it would be difficult. They just announced earnings, so there's no undisclosed material information to keep them from buying in the open market. The only other rule I'm aware is they can't purchase more than a fourth of the daily volume in a single day. So they could buy $500-$750k dollars of shares a day for the next three months until the next earnings release. 60 trading days = $30-$45m of stock if they wanted.
The truth is, for the long term health of the company, they should buy whatever provides the biggest bang for the buck on any given day. Right now, common shares are 33% or so below book value. What are the bonds trading at?