And as has been pointed out, many of those co-signers were not qualified, especially the man from AEI.
You could also use the American Physical Society as an example. The vast majority of members subscribe to the global warming science, but not 100% of them. But because the vast majority does agree, the Society took the official position of agreeing with the science of global warming. Giaever's resignation from APS doesn't change the facts of APS official position.