re: let's keep NASA focused on 'space"
The two statements are essentially equivalent.
The only reason that people are tugging your chain about making NEO detection a private endeavour is that it is equally unsuitable to be private as is a Mars mission, under current circumstances.
if you could rationally debate the virtues of different NEO detection and mitigation schemes without screaming that the sky is falling, and consider how an integrated program of space exploration will ultimately acheive all goals, despite different sub-priorities and agendas, then we wouldn't tug that chain...