[Alan]

The word 'mainstream' has positive connotations in scientific communities. Mainstream scientists are those who accept the most commonly established premises of a field, and thus keep contributing to the main body of such field. Maybe they're wrong, maybe they're right, but it's up to unorthodox branches of each field to come up with observations and research that gives satisfying alternate explanations to a phenomenon than the mainstream scientists give, and it's the duty of the mainstream body of each field to account for these alternative explanations.

Ironically, you people are the ones making their remarks political by inferring the social and political connotations to the word 'mainstream' in common language instead of taking it as the scientist uses it because, you know, he's a scientist.