Board Thread:The Panopticon/@comment-197.86.143.126-20200606192351/@comment-25041817-20200606220703

Could it not be possible that, from the Time Lords' perspective at least, the Monk hasn't left yet. The First Doctor implies in The Time Meddler that the Monk left Gallifrey fifty years after he did. Could there be wiggle room, there?

As for the Third Doctor not acknowledging the Monk as a Time Lord foe, well... the Monk's not exactly a top tier villain. Even his own wiki page states he's more of a "wannabe" villain. It could just be the Doctor doesn't see him in the same league as the Master and Omega, thus dosn't even bother with a comparison.