The report/justification for the removal is simply incorrect. Linux still supports s390-*-linux-gnu in user mode. The GNU toolchain is maintained, and the glibc testsuite is in good shape. Some distributions still support s390 (31-bit) applications. Others (Fedora 24 or later, for example) no longer do so.

I expect that 31-bit s390 Linux Python is really unusual these days, so removing it could still be fine, but lack of support from the GNU toolchain or the Linux kernel is not the correct justification for its removal.

If you have questions about the maintenance status of various parts of the GNU toolchain, please feel free to reach out to any of the GNU lists.

https://gcc.gnu.org/mailman/listinfo/gcc
https://sourceware.org/mailman/listinfo/binutils
https://sourceware.org/mailman/listinfo/libc-alpha