Since we are dealing with conservative scientific circles, we can be sure that anything that is unorthodox, especially backed by little empirical evidence will be rejected strongly.

But we need the sense of strong rejection to be conveyed by the phrase "tantamount to ___________";

tantamount to heresy is the best choice. Heresy means belief or opinion contrary to orthodox religious (especially Christian) doctrine.

tantamount to eccentricity and tantamount to reversion do not convey the same strong sense of rejection.

Now it is logical to conclude that any such scientist who embraces the unorthodox will be thrown out of these conservative scientific circles. He will be excommunicated. In this context, ostracized is the best or in fact the only choice.

lionized is the exact opposite of ostracized.
vanquished does not go well with the earlier choice heresy. For usually those who commit heresy are ostracized and not vanquished.