"...At what point does sexist behavior get taken seriously?"
In fairness, Myers' husband wrote a rather scathing Vanity Fair article on Bill Clinton (which drew a somewhat bizarre and equally scathing response) and was only in the Clinton White House for its first two years--missing the whole Lewinsky episode. She did (rightly) complain when she found out that she was being paid less than subordinates with lesser responsibilities.
However, Bill Clinton's problems with "bimbos" was not something he developed in Washington. This has been a lifelong problem for him, and for Myers to now decry sexist behavior from Obama's speechwriter towards a Hillary image is at least forgetful, if not disingenuous.