Does whatever Creative Commons license the author selects on bioRxiv, including the no derivatives option, prevent the author from entering into a different license with ACS?
No. Creative Commons licenses are non-exclusive and do not transfer copyright. This means the author can enter into a different agreement with ACS. Anyone who uses the author’s work from the bioRxiv server must abide by the terms of that license and anyone who uses the author’s work from an ACS journal must abide by whatever license the author has selected. Ideally the author would be consistent in their choice of license but this is not legally required.