From the category rules:

"Please do no submit Legacy Collection PC version runs under the PC platform of these leaderboards; that is specifically for the original PC release from 1998. Alternatively, runs done on the Man X Legacy Collection version on any platform may be submitted on the Mega Man X Legacy Collection leaderboards: https://www.speedrun.com/mmxlc#X4 "

If somebody were to time out the loads of the various Legacy Collection platforms, they could be moved back to these leaderboards w/ time conversions like the 1998 PC version, but until then XLC runs will remain on the XLC leaderboards along with X1, X2, X3, & X8.