All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
This misconception is only confusing to those who do not have enough knowledge to refute misconceptions. It appears to us from your previous questions that you insist to subject yourself to misconceptions. There is no doubt that this greatly endangers your faith, because exposing oneself to misconceptions will eventually lead to being affected by them, even if it is something insignificant, like the one you mentioned.
The Prophet warned his Ummah against misconceptions and encouraged Muslims to stay away from them. 'Imraan ibn Husayn narrated that the Prophet said: "Let him who hears of the Dajjaal (Antichrist) stay far from him, let him who hears of the Dajjaal (Antichrist) stay far from him, let him who hears of the Dajjaal (Antichrist) stay far from him, for a man will come to him thinking himself to be a believer but (eventually) follows him (the Dajjaal) because of confusion (misconceptions) the Dajjaal causes him to have (about faith)." [Ahmad, Abu Daawood and others]
Moreover, accompanying deviant people is very dangerous to your religion, because they will not stop from casting misconceptions and doubts on you, and if you are not enlightened with knowledge to refute these misconceptions, you will eventually become like them, we seek refuge in Allah from this. So fear Allah and cut your relationship with such deviant people with religious innovations and don't listen to their misconceptions. This is our advice to you, so be heedful.
The misconception, which this person mentioned to you, regarding the alleged prophecy of their leader, can be answered in two ways:
First: The quote you mentioned from 'Aa'ishah and which As-Suyouti mentioned in Ad-Dharr Al-Manthoor is not authentic and cannot be attributed to 'Aa'ishah, . Ibn Abu Shaybah reported it from Husayn ibn Muhammad, who said "Jareer ibn Hazem narrated to us that 'Aa'ishah said: "Say: 'The last of all Prophets', and don't say: 'There is no prophet after him.'" The inauthenticity of this narration is well known even to the very beginners in the sciences of Hadeeth. This is because they are aware that the chain of narrators for this statement is interrupted and is not from 'Aa'ishah, because Jareer ibn Hazem did not hear directly from 'Aa'ishah. As a matter of fact, he did not even live during her time, as there were decades between the death of 'Aa'ishah and the birth of Jareer ibn Hazem. 'Aa'ishah, may Allaah be pleased with her, died on the year 58 or 57 of Hijrah, and the one who allegedly narrated from her (Jareer) died on the year 170 of Hijrah!! He was born in the late 80s of Hijrah. Some mentioned that he was born five years before the death of the Companions Anas ibn Maalik, . It is known that Anas died in the year 91 or 92 of Hijrah.
Second: If we suppose, for the sake of argument, that the narration from 'Aa'ishah was authentic, then it would mean that 'Eesa the son of Maryam, may Allaah exalt his mention, is a Prophet and he will descend at the end of time, so don't say: "There is no Prophet after him", because he ('Eesa) will descend after him, but Allah will not send a Prophet to mankind with a new revelation after him. The statement is meant to restrict the phrase: "The last of all Prophets" without appending the words "no Prophet after him." One thing that confirms this is that when As-Suyooti mentioned the statement of 'Aa'ishah, he immediately mentioned afterwards the statement of Al-Mugheerah ibn Abu Shu'bah, which was also reported by Ibn Abu Shaybah, that a man who was in presence of Al-Mugheerah, said: "Muhammad is the last of all Prophets, and there will be no Prophet after him." Al-Mugheerah, hearing this, said to him: "It would have sufficed if you said: 'The last of all Prophets', because we were told that 'Eesa, may Allah exalt his mention, will come. Once he comes, he would have been before him (he was sent before the time of the Prophet ) and will come after him (as well)."
Al-Aloosi said in Rooh Al-Bayan: "As for the statement of 'Aa'ishah, "but do not say that there is no Prophet after Muhammad”, the reason she would have said that, Allah Knows best, is lest some people would think that the narrations of the descent of 'Eesa the son of Maryam at the end of time were revoked.
The fact of the mater, is that there will be no Prophet after the Messenger of Allah because even though 'Eesa will descend after him, he was there before him, and continues to be alive after him until the time when he descends. However, he will follow the Sharee'ah (legislations) of the Prophet Muhammad (i.e., will not come with a new Sharee'ah)." [End of quote]
Allah Knows best.