Assalaamu alaykum. I resubmit my original question as you requested, with a little elaboration:
Assalaamu alaykum. Did Abu Bakr, may Allaah be pleased with him, not allow apostates into the army even after their repentance? And did ‘Umar, may Allaah be pleased with him, although he did accept them into the army say not to make them the Caliph?
It was something along these lines. If possible, please provide references. May Allaah reward you. As for the statement not to make them the Caliph, is it true that ‘Umar, may Allaah be pleased with him, said in regards to apostates that you must not choose them to ruleover the Muslims, even if they repented, because they can not be trusted?

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, sallallahu ‘alayhi wa sallam, is His slave and Messenger. 

Shaykhul-Islam Ibn Taymiyyah mentioned something to this effect. He said, “Abu Bakr, may Allah be pleased with him, did not appoint anyone from the apostates even if they returned to Islam, out of fear of their corrupt intentions...” [Majmoo’ Al-Fataawa]

Ibn Al-Atheer while talking about Al-Muthanna ibn Haarithah and the conquests in Iraq, wrote, “He went to Al-Madeenah to inform Abu Bakr of the news about the war and to seek his permission to employ the ex-apostates whose repentance was proven sincere as they were more eager to participate in jihad than others (in order to atone for their sin)...” [Al-Kaamil fi At-Tareekh] This indicates that Abu Bakr, may Allah be pleased with him, forbade them to fight in the Muslim army.

As for the fact that ‘Umar, may Allah be pleased with him, permitted their enrollment in the Muslim army, we could not find any reference to that in the books and writings of the early scholars. The contemporary scholar Dr. Ali As-Sallaabi, wrote in the biography of ‘Umar ibn Al-Khattaab, may Allah be pleased with him:

"He then commanded Al-Muthanna ibn Haarithah to advance until the army catches up with him, and he commanded him to recruit the ex-apostates whose repentance was proven sincere." He did not mention anything about permitting them to rule over the Muslims or that a lack of trust was the reason for not appointing them as rulers. Nevertheless, it is well-known that ‘Umar, may Allah be pleased with him, was very strict in appointing governors. It was narrated that he said, "Whoever appoints a leader out of a group while he finds in that group someone who is more pleasing to Allah has betrayed Allah and His Messenger and the Believers.”

Allah knows best.