Aquinas thought he knew - these men committed suicide, which is a mortal sin, and cannot have repented of it while they were alive by the very definition of suicide, as it was their final act. Was Aquinas wrong?
Man is made master of himself through his free-will: wherefore he can lawfully dispose of himself as to those matters which pertain to this life which is ruled by man's free-will. But the passage from this life to another and happier one is subject not to man's free-will but to the power of God. Hence it is not lawful for man to take his own life that he may pass to a happier life, nor that he may escape any unhappiness whatsoever of the present life, because the ultimate and most fearsome evil of this life is death, as the Philosopher states (Ethic. iii, 6). Therefore to bring death upon oneself in order to escape the other afflictions of this life, is to adopt a greater evil in order to avoid a lesser. On like manner it is unlawful to take one's own life on account of one's having committed a sin, both because by so doing one does oneself a very great injury, by depriving oneself of the time needful for repentance, and because it is not lawful to slay an evildoer except by the sentence of the public authority. Again it is unlawful for a woman to kill herself lest she be violated, because she ought not to commit on herself the very great sin of suicide, to avoid the lesser sir; of another. For she commits no sin in being violated by force, provided she does not consent, since "without consent of the mind there is no stain on the body," as the Blessed Lucy declared. Now it is evident that fornication and adultery are less grievous sins than taking a man's, especially one's own, life: since the latter is most grievous, because one injures oneself, to whom one owes the greatest love. Moreover it is most dangerous since no time is left wherein to expiate it by repentance.- St. Thomas Aquinas, Summa Theologica
Was Aquinas wrong?
Aquinas was right about everything.
Aquinas made no judgment about the souls of particular men, as some on this thread are doing.
Also, eschatological understanding has developed beyond Aquinas.
The Pope is not wrong to pray for the repentance of these horrible men.