The issue of propagation delays with bigger blocks was fixed with xthin blocks (aka: compact blocks) months ago. That is no longer a valid reason for limiting the block size.
And to clarify, the software may have been released (in Bitcoin unlimited's release), but is not used by the Bitcoin network as a whole. Very few nodes are running this implementation. And to many is untested/unproven
Fact: Both xthin and compact blocks are different implementations of the same idea. Both have already been implemented and released and are in active production.