Then somebody drinks and everybody judges him when the Bible does not explicitly say that we should not drink. It says we should not get drunk, but not that we shouldn't drink. However, the Bible does explicitly say that we should not judge our Christian brother exercising his liberty, and no one should be our judge with regards to food or drink. That is explicit in the Scriptures. People exalt man's rules to the level of God's law, and in so doing violate God's explicit law.
Sports are worldly and it is a sin.
They don't allow it. That sounds bizarre to us because we love sports, but that is just their thing. It is an example of their particular rule at the time that they made equal with God's law. They are very sensitive about it. If you are going to adopt a rule that applies to all Christians, you ought to be able to identify an explicit Biblical prohibition.