What is the ruling on a father who recites the Two Testimonies aloud, causing his son to lose focus and doubt whether he has recited the Two Testimonies or not?

Scholars have unanimously agreed on the disliking (karahah) of vocalizing the tashahhud, because whispering it is from the Sunnah of prayer. Their evidence is the hadith of Abdullah ibn Mas'ud, may Allah be pleased with him: "It is from the Sunnah of prayer to conceal the tashahhud." The disliking is emphasized if it leads to disturbing other worshippers. For this reason, the Prophet, may Allah's peace and blessings be upon him, forbade some worshippers from vocalizing the Quran over others, saying: "All of you are privately conversing with your Lord, so do not vocalize the Quran over one another." The father should be gently and politely alerted to this.