As far as a I know, Ott has not publicly confessed to claim the Pope as being the Antichrist; so, Ott appears to be “credible”.
I am sincerely glad that you have brought this topic up, @JonNC. I was completely unaware of this. After researching as much as I could online, this is perhaps the best information that takes into account the possibility of non-Bishops ordaining priests:
The ordinary minister of the sacrament is the bishop, who alone has this power in virtue of his ordination. Holy Scripture attributed the power to the Apostles and their successors (Acts 6:6; 16:22; 1 Timothy 5:22; 2 Timothy 1:6; Titus 1:5), and the Fathers and councils ascribe the power to the bishop exclusively. First Council of Nicaea (Canon 4) and Apostolic Constitutions VIII.28 — “A bishop lays on hands, ordains. . .a presbyter lays on hands, but does not ordain.” A council held at Alexandria (340) declared the orders conferred by Caluthus, a presbyter, null and void (Athanas., “Apol. contra Arianos”, ii). For the custom said to have existed in the Church of Alexandria see EGYPT. Nor can objection be raised from the fact that chorepiscopi are known to have ordained priests, as there can be no doubt that some chorepiscopi were in bishops’ orders (Gillman, “Das Institut der Chorbischöfe im Orient,” Munich, 1903; Hefele-Leclercq, “Conciles”, II, 1197-1237). No one but a bishop can give any orders now without a delegation from the pope, but a simple priest may be thus authorized to confer minor orders and the subdiaconate. It is generally denied that priests can confer priests’ orders, and history, certainly, records no instance of the exercise of such extraordinary ministry. The diaconate cannot be conferred by a simple priest, according to the majority of theologians. This is sometimes questioned, as Innocent VIII is said to have granted the privilege to Cistercian abbots (1489), but the genuineness of the concession is very doubtful. For lawful ordination the bishop must be a Catholic, in communion with the Holy See, free from censures, and must observe the laws prescribed for ordination. He cannot lawfully ordain any except his own subjects without authorization. - http://www.newadvent.org/cathen/11279a.htm
Now, for the sake of argument, let us say that you are absolutely correct in claiming that the Pope dispensing the function and sacramental power of ordaining priests to Abbots, among other non-Bishops, has occurred in the past. It would seem, at least to me, that this privilege derives its efficacy from the jurisdiction of the Pope, such as Pope Boniface IX dispensing the authority and sacramental power to ordain to Cistercian Abbots. In other words, it would be the Bishop of Rome ordaining through the Abbot as the Abbot would act as an auxiliary Bishop, if you will. Not solely the authority would derive from the Pope, but that actual sacramental power that all Bishops have.