As others have clearly demonstrated, 危机 does not simply break apart into
危 short for 危险 (danger) and
机 short for 机会 or 机遇 (opportunity).
In short, that's not how Chinese works. However, it is sometimes used idiomatically. Examples:
Searing Baidu ...
QUOTE:- "Contextually 机 appears in lots of words where it doesn't bring the meaning of "opportunity"
That's not entirely true, for in other areas it does. We therefore have 机 不 可 失， (don't let slip an opportunity)
Please don't get me wrong. I am not disputing that 机 does have many other meanings, context which have nothing to do with "opportunity"
What is so wrong interpreting 危机 (crisis / dangerous situation) which is made up of:-
危 险 = danger (definitive meaning)
机 会 = opportunity (definitive meaning)
as "within a situation of danger, (a crisis), there are also opportunities to be had"?
Just as in English, the phrase "bitter-sweet" has to be wrong because you cannot have anything both bitter ...
This thread would never be complete without the "urban-dictionary" style (i.e, slang), modern example for such idiom, the good old 吹牛, or its R-rated version 吹牛逼.
It generally means to brag about something, which could be true but usually isn't.
But you can coin four-character words to express it more accurately. It looks like that you mean academic claims.
Let me have a try:
论訇证寡（The claim is thunderous(figurative), but the evidence is little.）
Note: Only in writing you can coin such words. Otherwise people won't understand you.