It's not feasible or practical for them to recompile their code?
> the business activity that is main source of a company's profits and success
Maintaining libraries is not the core business of those that use those libraries, most of the time. That's why people use libraries.
When they said "maintain", I read it as short term, doing this if and when for all libraries down the dependency chain. Or, compile as x86, and wait until external resources push for the support.
I'm curious to compare what the GTK build process looks like as a universal binary; I think RawTherapee has done it.