A freshly created MGT reports the following after mounting:
hoeplustre06-mgs-mds-n1 kernel: Lustre: 371323:0:(osd_handler.c:7070:osd_mount()) MGS-osd: device /dev/mapper/vg_mgs-mgs was upgraded from Lustre-1.x without enabling the dirdata feature. If you do not want to downgrade to Lustre-1.x again, you can enable it via 'tune2fs -O dirdata device'

My understanding is that dhrdata is not required on the MGT so the check should be removed for MGT devices or it should be set when running mkfs.