If you want to argue further cite legislation which purports to support your position. I will spend time to research it and respond.

Business owners are required to convey that people who enter their premises are masked. However that is only half of the law. The other half of the law is that there are exceptions. Those exceptions include medical (whether they be physical or psychological, difficulty putting on a mask, and any grounds under the various human rights codes under the provinces including religions and creeds). If a patron says, "I'm exempt", businesses have absolutely no right to demand proof.

Reopening Ontario A Flexible Response to COVID-19 Act, 2020. This law applies across Ontario and prevails over any municipal bylaw that contradicts this regulation.

Exemptions under the act relevant to this case include:

(4)(g) has a medical condition that inhibits their ability to wear a mask or face covering;

(h) is unable to put on or remove their mask or face covering without the assistance of another person;

(j) is being accommodated in accordance with the Accessibility for Ontarians with Disabilities Act, 2005;

(k) ** is being reasonably accommodated in accordance with the Human Rights Code**

The Trespass to Property Act of Ontario DOES NOT apply when exercising masking exemption since the act states:

Trespass an offence 2 (1) Every person who is not acting under a right or authority conferred by law...is guilty of an offense.

It is trespassing if the owner asks you to leave ONLY IF you are there NOT acting under a right or authority conferred by law. Exercising masking exemption IS a right conferred by law.