Wearing and eating at the Masjid

Q 2: One of the attendants of the Masjid (mosque) claims to have knowledge of religion and, thus, gives Fatwas of his own and causes confusion among the Muslims by sorting Halal (lawful) and Haram (prohibited) according to his own opinions. He also says that he does not acknowledge Tafsir (exegesis of the meanings of the Qur'an), claiming that what Allah states in the Qur'an is very clear and needs no referral to all books of Tafsir. An example of his Fatwas is claiming that it is Haram to change one's clothes inside the Masjid. When we asked him about his evidence, he cited the following Ayah (Qur'anic verse), (Part No. 22; Page No. 351)  O Children of Adam! Take your adornment (by wearing your clean clothes), while praying [and going round (the Tawâf of) the Ka‘bah,] We told him that the Ayah states nothing about the unlawfulness of changing one's clothes inside the Masjid and referred to the Tafsir, but he said that he does not acknowledge any Tafsir.Moreover, we have a hall over the Musalla (a place for Prayer) in the Masjid. Some Muslims offer `Aqiqah (sacrifice for a newborn) and bring it to the Masjid so that its attendants will eat from it. This person says that this is Haram because the Masjid is a place for Salah (Prayer), Dhikr (remembrance of Allah), and Du`a' (supplication). We told him that the Masjid can be a school, a university, a military college, a place for worship and the Muslims' gathering, and where Muslims can settle their disputes as in the case of the Sunnah (whatever is reported from the Prophet). However, he was not convinced and recited the following Ayah, And the mosques are for Allâh (Alone): so invoke not anyone along with Allâh. Thus, this person always causes confusion among the Muslims, especially that he utters such claims after each Salah.My question is: Should we prevent this man from entering the Masjid? Would we be sinful if we do? We have spared no effort to convince him but it was all in vain and he even says that he should enjoin good and forbid the evil. Please advise, may Allah reward you with the best!