Two possibilities:
1: He since realized the need for that (possibly after having put some points into WIS for various reasons), and has been backfilling his Survival stat since then.
We have to keep in mind that the party was still mid-level back then, and they've gotten considerably more powerful since then.
2: He's lying to Roy about his reasons because, while he's certainly closer to Chaotic Neutral these days than he was way back when (maybe even there and progressing towards Chaotic Good!), it ain't like he's going to go completely soft on Roy :).