The US government have already "assisted" plenty. Every assist is a setback. IE. Snowden's revelations, encryption standard weaknesses, backdoored devices, etc.
No, but that is exactly why Apple might be a little bit reluctant to go for assistance. It's a bit like going to the neighborhood burglar to ask him how to secure your house. "I'll be right over to take a good look at your property" is not the answer you think it is.
That's an absurdly narrow view of the USG security positioning. USG pours billions of dollars into defensive infrastructure through a number of methods.
