More than their time to maintain? Do you have any idea how expensive a developer’s time is? He could easily be making 120 or 200k a year with his talents
you can’t complain
You absolutely can. When this business has made zero fuss about it for more than a decade and has even welcomed them with open arms, even having meetings with them directly on many occasions, then YES you CAN complain when they suddenly do a 180 without any warning.