I don't know who / what dealer is telling you that, but Komatsu doesn't have any such policy restricting the sale of manuals. If your local dealer won't sell you a manual I am sure Komatsu would like to hear about it. You can contact their service & warranty department at warranty at komatsuna.com and they will be happy to assist you.

I just called my dealer in Dallas, TX and was told that Komatsu will not sell service manuals. He said it was a Komatsu thing. He said he could sell me a parts manual, but not service. I guess it is time to sell my forklift!

Call your local dealer and they can order manuals (printed or USB drive. The Komatsu America website has a "Find your Dealer" page, just check forklift only and it will take you there.