I disagree. If he's actually willing to sign a new contract, then keep him around for this season: it'll be good to have two genuinely decent left-backs (although Davies is definitely better than Rose, Rose himself isn't too bad: not top six standard, but comfortably PL level, imo), and we can reassess his situation here after a year spent competing with Davies and (hopefully) improving under Poch.
It makes little sense to sell him if he's actually willing to stay, imo: the squad depth he offers may prove crucial as we enter the second half of the season and as cup competitions start piling up. Fryers won't cut it then. And, after this season's over, we can sit him down and say to him 'look, we've done right by you: we've given you a full-season as our undisputed number one left-back, and another as a fiercely competitive rotation option for Davies, with the latter demotion only occurring because you failed to impress in 2013-2014. Now, we'd love to keep you around as our second LB option full-time for as long as you want to stay in that role, but if you'd like to move on, we won't stand in your way.'
Whatever Rose subsequently decides, everyone'll likely be happy at that point.