I see both sides of that - Surrey do not have a genuinely top class wicket taking spinner (Batty is good for blocking up an end but has no great strike rate in FC cricket) and have tended to go for overseas options over the past few years, which have usually tended to be available for a few weeks then off again. Keedy is a quality bowler and, with sensible treatment, will have two to three seasons of FC cricket left in him (less convinced he'll last that long if he plays all the hita nd giggle stuff). So he is a reliable part of their team for a period of time.
For Keedy I suspect it was more than just the paycheck - at Lancashire he was second pick to Simon Kerrigan and possibly also behind Steve Parry. At Surrey he'll play most every game.