Just trying, without training properly, in a safe environment with someone who can help him if he starts losing control, is unlikely to end in him controlling the Sage Mode.
But if he knew how to balance it perfectly, it's possible he could absorb it, but even then I don't think so, I mean learning sage mode means perfectly balancing Nature chakra with your own physical chakra, so if you absorb someone's chakra, you're absorbing already balanced sage chakra, combined with your own chakra, puts the nature chakra out of balance, making it too weak and not a real sage mode. If you just absorb the Nature chakra from someone, if that's possible, the person you're absorbing from would have to of equal Physical chakra to you EXACTLY.
There is the option that you absorb the chakra from someone who is continuously taking in Nature Chakra, like with Naruto and Pain, Naruto was continuously taking in Nature chakra, so that it outbalanced his own, but got absorbed by Pain, so if Pain could balance it then, under those strict parameters I don't see why not. But in order to do that you'd basically have had to learn sage mode yourself, so it might just be worth learning sage mode and entering it yourself.
