'may not be plausible' is a correct and usable phrase in written English.
You can use it whenever you want to express doubt or lack of belief in something. For example: "His explanation of the situation may not be plausible."
These continuity assumptions may not be plausible if agents are able to manipulate the running variable.
Saving for a house may not be plausible given that you still lack experience, but paying your own bills is something you can do now.
Due to the limited sample size, it may not be plausible to draw firm conclusions from these data yet.
In fact, however, assumptions that Cox proportional hazards modeling required may not be plausible in many situations [ 22], especially in biomedical field.
32 Gutiérrez-Fisac et al suggest that a socioeconomic interpretation may not be plausible, as most studies adjust for socioeconomic position.
Besides, it may not be plausible to compare results from a randomized clinical trial to our results from a cohort study.
Learning about treatment effectiveness with a view to treat patients in the larger outside population, as in the traditional fixed randomised design, may not be a plausible goal.
These revised versions of the Consequence argument may not be as plausible as the original version, but it still looks as though the compatibilist is in trouble.
Notions like belief, desire, hope, fear, etc. are folk notions and, as such, it may not be utterly plausible to expect (eliminativist arguments aside) that a scientific psychology will preserve the exact contours of these concepts.
Because residence probabilities were not affected by parental exposure to atomic bombs (unpublished data), migration may not be a plausible explanation for this finding.
