"is not unquestionable" is correct and usable in written English.
It implies that something is open to question or debate. For example: "The rightness of that decision is not unquestionable."
This may be related to the way the authors calibrated the cystatin C measurement, which was not unquestionable.
Mr. Erdogan also said "Of course we salute all of Lausanne's successes, but Lausanne is not an unquestionable or holy scripture.
Information is not passed down as unquestionable truth here.
What matters is not whether one believes in an unquestionable heavenly God or an infallible earthly one; it is the attachment that poses the problem.
In a year of political astonishments, an unlikely turn in the Presidential campaign emerged in late January, when polls began to suggest that Hillary Clinton was not the unquestionable choice of black voters.
GMO assessment is a complex issue (not a complicated one), and risk assessment studies, no matter how sophisticated they are, cannot produce definite and unquestionable results because it is not merely a matter of an objective science delivering 'the facts'.
Even more problematic are description terms like "the present king of France" and an unquestionable semantics of the (true) statement that "the present king of France does not exists" is not easy to provide.
It is not possible to conclude that RVFV is endemic in the region, although the presence of IgG antibodies is unquestionable.
It is also unquestionable that long-term cultivation of the cells on the gels or in the liquid cultures is not appropriate to keep the genotype of the cells.
Using wages or earnings is however not unquestionable.
