There is an issue here about how close should you have two major operations and it's not really about recovery. One member here had their second hip (or was it knee?) done 5 or 6 days after the first. The reason that was safe was to do with the thrombosis issue. The crucial period for thrombosis risk is between 1 and 6 weeks which means that no surgeon and/or anaesthetist would be wise to entertain another major surgery within that time period unless it was an emergency situation.
So, how long to wait before doing the second hip? Could be any time once that crucial period is over.
And finally, it seems good sense to have another few weeks to get back to normal functioning and over the painful period so you know you have a nice sound hip to lean on! Plus, he could always be playing it safe on the dislocation risk.
Of course, the alternative is always to have them both done at the same time but probably a bit to late to seek out a surgeon for that now.