According to this article, it seems they want to sell it directly to chat applications.
"There's a company called Thorn that is lobbying for the scanning contract and would love to get a government mandate for its software to be installed into your chat clients," he said.
Apparently Apple didn't want to pay and developed their own in-house, only to scrap it after complaints from the public.
I would guess they are simplying sponsoring this legislation sincerly without understanding the privacy ramifications if it passed.