The issue wasn't whether they accepted, it is demanding an immediate acceptance before you left the field. I find that approach distasteful, give the family a chance to talk in private and make sure this is what they want. In our family, neither my wife nor I commit to any financial decision without at least consulting the other, and I frankly don't know what a team's dues will be before a tryout, even if a friend tells me what they were last season I want to hear it from the coach before I consider it offiical.
I personally have always ended tryout season when we accept an offer, but there are some who may not know about an opening when they accepted, and legitimately think after accepting that they should at least look at the new opening. It isn't my style, but it isn't for me to judge others either.
We had a coach do that 2 years ago. He called the same night as the tryout and wanted an immediate answer. My husband and kids were at the Braves game at the time. I was like I am not making this decision without my husband and my daughter (the actual player) here! Are you nuts? He was not happy. We did not go with that team. The whole "desperate" vibe was overwhelming.