If pharmacists can withold treatment they deem wrong, can nurse do the same? Hospice workers? Withhold anti-psychotics? Withhold dextrose and saline? Withhold anti-coagulants?
Would it also be ok for pharmacists to replace birth control pills with a placebo?
Pharmacists are private citizens involved in private businesses; therefore they should be allowed to choose which legal drugs they wish to sell or not sell. If you don't like it find another pharmacy. If these pharmacists were government employees, then they would be obligated to sell what their employer dictates. Health care workers participate in purely moral decisions every single day.
The medicines and "treatments" in question are not for illnesses, they are purely elective and are rarely sought as a life saving matter. Should all doctors be required to perform liposuction just because a patient asks for it?