Anyway, Not sure who the Mystical Bidy is, but I dare say we all have our own contenders from the old ladies who attend Mass.
Personally I've known some really lovely, charming and holy old ladies over the years. Family members (of course) then various matriarchs, old spinsters and even one who helped run a church bookstall who went off to become a nun.
Then of course there's been the daughters of the 60s in various parishes who demand communion in both kinds and try to put various priests under so much pressure as to take over parish life.
So here's my opinion, for what it's worth. To be a true Mystical Bidy of Christ you have to love Our Lord in the Sacred Species and abide by Church teaching and traditions down the ages.
That goes for Old Geezers too... Which I am rapidly becoming.
Praise The Lord! (But not with a tambourine).