I'm gonna be pretty suspicious of any external party telling a company they don't work for that they have enough money to do x. None of us know what Valve's budgets, expenditures, other projects in the works, employee availability, employee expertise, etc they have. It's just not reflective of how large development organizations work. Not to say this wouldn't be worth Valve focusing on, but we just don't know enough about their finances to make that kind of call.