The verse in question deals with Abraham and his son, Ishmael (peace be upon them both). Abraham saw in a dream that he was sacrificing his firstborn and at that time only son, Ishmael. When he explained his dream to his son and sought his opinion regarding it, Abraham found Ishmael as one willing to cooperate with the command of God. When they both submitted to the command of God, by fulfilling the vision in the dream, the trial was finished and a ram was provided to be sacrificed in Ishmael's stead. This is how they "became Muslims" in the verse. Islam means submission to the command of God and a Muslim is one who submits to God's commands.
As for the Tashkent MSS, then personally I have not read it and I doubt that the questioner has either. Perhaps one of the reasons why this is one of the 60 questions Muslims don't like to be asked is because people who ask these questions don't have any real knowledge of the Qur'an or Islam and are afraid to research the integrity of their own scriptures. I would suggest for the questioner to learn Arabic, then learn how to read Kufic script, then provide the evidence of this backed up with the statements of scholars of Qur'anic exegesis and Arabic language, and then come and talk to me about what the Tashkent MSS says. Until then, I cannot explain any variation as I don't know of one, and must continue to accept and inform of the perfection of the Qur'an.