Complex sentence: He argues that such bias contradicts AEA's claim of non-partisanship, that it harms the economics profession by favoring certain opinions over others, and that it cripples the spirit of discussion that AEA seeks to promote and may lead to intellectual complacency.
Split into simpler sentences: He argues that such bias contradicts AEA's claim of non-partisanship, and that it harms the economics profession by favoring certain opinions over others. Favoritism cripples the spirit of discussion that AEA seeks to promote and may lead to intellectual complacency.