St Severus considers the issue of reconciling with groups who venerate some people who are 'controversial'. It is clear that there is no obstacle on our part in allowing a reconciliation with the Chalcedonians on the basis of controversial figures such as Leo. He says...
In dealing with abstentions with regard to names preserved in the sacred tablets we must in fitness duly compare the things of which the sacred Scripture said that, when they fall into water that is contained in small vessels, they pollute it, but, when into pools or wells or cisterns containing many streams, they cause no stain or pollution. For the law of the divine Spirit said thus: «And every drink that ye shall drink in any vessel shall be polluted; and everything on which anything from a dead body falls is polluted. However fountains of water and pools and cisterns of water shall be pure».
This principle then ought to be observed in the present case also. If a man separates from many on the ground that they are infected with heresy, or that they communicate with those who are infected, let him with all his power maintain abstention from the dead body, and not mention even the name of those who are under suspicion and not genuine, lest it fall and pollute the purity of the communion. But, if the holding of the orthodox faith, and an anathema of every heresy reigns in the churches, and whole countries and provinces, and populous churches, confess one uncorrupted confession, then names which are thought to pollute are inundated by the multitude of streams.
It is good that no particle of a dead body should be introduced even into a large quantity of water; but if perchance it in fact happen to be introduced, it is cleansed by the quantity of streams, and swamped by the quantity of cleansing. We find that in fact the holy fathers also who were in former times upholders of the right word managed these things in this way. Show us from the compositions of the doctors of the church that, after so large a number had found fault with the faith of the 318 at Ariminus [sic], any question was raised about the names of those who had died. And, not to make the letter tedious by using many words, let us pass on in mind to times that are near and not far removed. We find that the holy Timothy, he who underwent long exiles, united with everyone in the Encyclical, and communicated with Paul bishop of the city of the Ephesians, and Peter who had become prelate of this great Christ-loving city of Antioch, while names under suspicion were preserved in the sacred tablets; and the holy Cyril, when he united with the Easterns after the deprivation of Nestorius, when many bishops had died, and had departed under the stain of the Nestorian heresy, made no inquiry about names.
If therefore those who set great store by strictness in respect of such names say that the oblation is not pure, let them know that their strictness also draws its origin and existence from such communion, and descends from that source as from a root. For the saintly Timothy, as we have said, consented to hold communion with those of like opinions in company with such names, he whose grandsons they are who now with a boastful front loudly proclaim, «You shall not approach me because I am pure». And this we say superfluously, that some of the bishops in the cities of the Easterns set even this also straight, and ceased to mention all such names: for others found it impossible to set this same thing straight; and it was not right for such a reason for them to enter on wrangles, and set themselves in array against the enthusiasm of the people of the cities, in order that they might suffer shipwreck in the most essential things.