If their concern is genuine (rather than a way to get a look under the hood of a competitor for the current sellers of such services) there are multiple ways in which they could get their verification without inside information on how Theranos does its thing.
I'm not sure how available the tests are yet, but if it's available really anyone could test it. However, it requires a sample of a large diverse population to get statistical significance and that isn't cheap, which is why most academics probably aren't interested in doing it.
The company being non-cooperative is it's right - it's just not good science.
When the results come back, tabulate and compare.
If there are major discrepancies, they'd probably turn up in the first few dozen tests. But you could run this for hundreds of people with a single analyst, and just a few doctors soliciting their patients' participation, and without needing cooperation from Theranos.
To be valid, you'd want to go in and supply a bunch of baked-samples which should produce a certain definitive result, without the tester knowing this in advance.
Storing 'baked-sample' blood, or doing extra tests against people who weren't otherwise needing tests, couldn't possibly be as representative. Diverting a few drops from tests that are already going through the traditional process, for research/calibration purposes, is likely already authorized by existing patient relationiships. Your "n" for analysis, across any disorder or rare test, would quickly exceed what's "recruitable" for some formal study.
Look at the list of Theranos partners/customers who have brought them to "cash-flow positive": hospitals, drug companies, insurance companies, and the US military.
It's naive to the ways of industry R&D to assume that such constant cross-validation hasn't been (and isn't still) happening.
Proving that it works is a much harder problem that probably only Theranos is willing to finance.
Proving reliability does rely on examining internal methods, and showing they are consistent and reliable.
I concur it somewhat lends to Theranos' credibility that no competitor is disproving their accuracy.
So the right answer is to repeat the experiment. Perhaps many times. You'll end up with a statistical judgement of consistent inaccuracy and while it'll be easier to prove (in terms of statistical strength) than showing accuracy, it'll still be (a) reasonably expensive, (b) generalizable research, and (c) less punchy for headlines.
(b) is especially concerning because if you publish generalizable research involving humans, as would be the only way to do this, then you have to treat it like a legitimate clinical trial and are responsible for many more legal processes, e.g. IRB approval.
I'm assuming they've done this study, but have refused to publish it for some reason. But this is the real question from the article - where is this study? You don't have to disclose the full technique for the test in order to publish the comparison.
> I'm assuming they've done this study, but have refused to publish it for some reason.
Because they're a bog-standard vertical integration play and if that fact comes to light before they are done using the hype train to raise money and grab market share then their competitive advantage will evaporate overnight. If they only release test results to interested parties under NDA it prevents public sector science from rebutting their claims to disruptive rather than incremental innovation, allowing the hype train to steam ahead unimpeded.