"Rise, Peter, and fulfill this pastoral office divinely entrusted to you as mentioned above. Give heed to the cause of the holy Roman Church, mother of all churches and teacher of the faith, whom you by the order of God, have consecrated by your blood. Against the Roman Church, you warned, lying teachers are rising, introducing ruinous sects, and drawing upon themselves speedy doom."
Well, since the Prots did not meet a "speedy doom", it would seem that Peter was either disinclined to hear Leo's petition or had need to attend to other, more important matters.
And given that the Prots went on to evangelize half the world and now account for roughly 2/5ths of Christianity (+700 million) - it would seem that the tree bore good fruit.
Ah, but a thousand years are as a day, and a day is as a thousand years :-)
There is no disputing the fact that as Christians, we are all part of the Body of Christ. So, the "good fruit" is not disputed. The "deposit of truth" is disputed, as the RCC is the only church that has claimed and can claim it. As for the "speedy doom," we are talking about a Church that traces its roots back 2000 years, and an offshoot going back 500...who knows what is to come? Seriously, though, "lying teachers" is the key--Prots profess the message of Christ as much as Catholics do, so where are the lies?