I lived in Boston (Back Bay section) in 1984 and went to Scooperbowl. That was their 2nd or 3rd year. Back then it was $2 ( I think) not more than $3. and they gave me a bowl and I was invited to fill it up (as often as I wanted). It was a warm day around high 80’s with high humidity. When I was through eating, I filled up the bowl they gave me and walked home as fast as I could without running. I am glad that it was in the common then because I was able to make it home with about 2/3 of the ice cream not melted. I ate what was left over the next few days.
The last time I visited Boston it was with my wife who had never been there. By coincidence, it was the week of scooperbowl and we went there and enjoyed the ice cream. $7. is getting expensive. Yeh it is good ice cream from the best sellers in town, but $7. might make me hesitate.
I reccommend that you go, but take a bowl and hide it and bring it in with you. For $7. you should be able to take some home for later. I don’t think the organizers would notice, you sneaking it out. (It is not New York). You can slip the bowl to a friend behind the rope.