Imagine that one day you go visit the headquarters of your favorite humanitarian organization.
You find out they use Windows and Macs and MS Office and all sorts of proprietary software.
Would you have the nerve to lecture them on that?
Would you have the skills to switch them painlessly to a more virtuous free system?
No, of course you wouldn't. And of course you shouldn't, because you would disrupt their operations, which are more important than a software license.