EMsHC are allowed because they are sometimes needed. This is discerned by the presider. I am a EMHC. I understand this. I also understand, though, that it is the perogative of individual Catholics to refrain from receiving from anyone but an ordinary minister, particularly when the person is already a regular communicant.
It is unquestionable that the Church encourages frequent reception. What you don’t seem to get is that this does not translate into a duty to receive Holy Communion at every opportunity, in spite of any reservations one might have. That is simply not true! Rather, the person ought to consider in every instance whether he or she is sufficiently well-disposed to receive worthily and reverently. This can include refraining when one is concerned about giving tacit approval of a possible abuse. I want to be careful not to accuse anyone who does receive, not taking that as complicity with any abuses taking place. Requiring that is going too far. If something is lacking, or if we are seriously concerned that something may be lacking, though, we do not sin by electing not to receive, and especially not if we are regular communicants in the big picture.
The individual communicant is the one that needs to discern when she is disposed to receive and what effect her reception will have on the Body of Christ. We are not bound to refrain unless we are not in a state of grace, have not observed the required fast, or something of that nature. Nevertheless, if we discern we are not well disposed, we do well to refrain. We do not sin nor lose sight of the Real Presence in doing so.
“You have heard that it was said to your ancestors, ‘You shall not kill; and whoever kills will be liable to judgment.’ But I say to you, whoever is angry with his brother will be liable to judgment, and whoever says to his brother, ‘Raqa,’ will be answerable to the Sanhedrin, and whoever says, ‘You fool,’ will be liable to fiery Gehenna. Therefore, if you bring your gift to the altar, and there recall that your brother has anything against you, leave your gift there at the altar, go first and be reconciled with your brother, and then come and offer your gift. Settle with your opponent quickly while on the way to court with him. Otherwise your opponent will hand you over to the judge, and the judge will hand you over to the guard, and you will be thrown into prison. Amen, I say to you, you will not be released until you have paid the last penny.” Matt. 5: 21-26.
IMHO, it is better to refrain from going at all than to receive the Lord with judgement in your heart about whether someone else is fit to be a EMHC. Certainly, it is allowed to refrain. It is allowed to refrain if you discern that the situation is in any way irreverent. It is allowed to refrain if you are concerned about being complicit with what you honestly believe to be an abusive situation. Strictly speaking, it is even allowed to only receive from someone you personally like, for that matter. That could be a venial sin, but it is **not **a mortal sin, such that you should fear dying before having a chance to confess it, if you have ever done it. It is way, way out of bounds to suggest that this attitude consitutes a mortally serious offense against the Eucharist. We are not allowed to make things up or insert our own sense of things when it comes to admonshing others concerning the gravity of their sins! We have to stick to what the Church teaches.
At any rate, no matter what her reasons, no one should ever judged for deciding not to receive, particularly not if the person is a regular communicant. It is the communicant who knows her heart, and God who will judge her heart, not any of us. That judgement should be considered every bit as serious a matter as sitting in judgement of someone else as being unfit to be a minister of the Blessed Sacrament, when the requirements the Church has laid down for fitness have been met.