I agree with you that baptism is not necessary for salvation. However, it is the first command to the Christian.
If the Christian fails to be obedient to this first command, it does raise the question of whether that person has truly accepted the Lord as savior and repented. There are of course medical reasons why a person might not be baptised. And I suppose that there may be other reasons that a person who has truly repented and placed their trust in Jesus might not be baptised such as lack of knowledge, but they are few and far between.
But becoming Christian does not usually make one fully obedient. God gave us many commands. It takes a lot of soul searching to become fully obedient.
What chapter and verse?
But when are we FULLY saved???