So those other examples mean you do have the burden of justifying your 'conspiracy' label.
As FooHentai originally said, "There is a clear evidential basis to infer the NSA's intent and capabilities in this area" - but it tells us nothing about this particular case, which remains speculation. One could say the odds have changed, but we still don't know anything about the real state of things.
The "'conspiracy'-label" is applicable regardless, whether we're talking about fact or fiction.
Likewise, if there's a backdoor in every new PC's CPU, and there's a three-letter agency presiding over that CPU vendor's jurisdiction that has a long track record of backdooring things, is it unreasonable to suspect that maybe - just maybe - that TLA is responsible?
Now of course the ex-con or the TLA can be totally innocent here, but if I were a detective, they'd be the first ones from whom I'd be asking for alibis.
The hypotheticals aren't comparable, nor is the prior available information - and even though the Intel AMT/ME situation is egregious, explaining it simply as "a backdoor" is an oversimplification.
I'd agree that probabilities with regard to what is reasonable to assume (the operative word here) shift as a consequence of circumstantial information, but you can't really draw any conclusions based on that - hence the burden of proof, i.e. the presumption of innocence in your analogy.