Discuss whether Tomas is behaving in a professional manner.?

Professional? Not totally, no. He has chosen to take a shortcut on a material difference which is contrary to GAAP. But, he has taken an action which is in synch with the conservative principal of accounting. I think it would depend on how important the 5:00 deadline really is. If the f/s are needed absolutely by that time, then they have a worst case scenario of where the company is at financially. If he can, however, he should refuse to present the f/s referencing the unknown error and either spend the o/t needed or postpone it until the next day.