I've asked him on Twitter but I'm not a celerity, so he won't reply.

I like the shirt and want to purchase it. Anyone know where it's sold?

I have no idea where the shirt is from but he does have thousands of people tweeting him at the moment so probably hasn't even seen you're tweet! Keep trying or maybe tweet his sister, she has less followers so you're more likely to get an answer

I doubt if he has got the time to respond.

not the exact same one but there's a very similar ralph lauren one

if you just google denim shirt with camo sleeves quite a few come up.