A strawman would be me saying something like "This is a good idea, but it is obvious it needs quantum cryptography to succeed, and as we all know, that is hardly commercially available in a form factor you could incorporate in a digital camera, hence the idea will never fly." (Yes, this is taken almost ad absurdum - but, hey, this is the Internet, after all. :))
Me arguing that this is a good idea which could be even better at no disadvantage to Poitras et al and for negligible extra development, however, is hardly a strawman.
Then again, I may be misunderstanding you altogether; English is my third language and I am struggling to understand what you mean when you suggest that I (paraphrased) say "This is too limited because it doesn't help people taking the camera"
Even Poitras' suggestion is intended to help once someone has taken the camera; you do not need encryption or anything per se as long as the camera is in your possession. (Assuming it is offline!) - It is when someone - be it the US Govt, a competitor, your friendly neighbourhood grunt, some guerilla in a disagreeable part of the world has taken it that limiting access to the images/footage is necessary.