The decision to discontinue the GTK2 support was made by the development team in order to put all efforts on the new GTK3.
The fact that XP support is also discontinued was taken into account by the team, but as @paperdigits said, MS support ended almost 3 years ago.
The use of GTK2 or GTK3 is not a build decision. It is defined in the code. So I regret that there is nothing I can do except to provide you the last 32 bit gtk2 “pixelshift” build in same location.