Perhaps I'm missing some boxing-related sarcasm(which wouldn't be a surprise, as I don't follow boxing), so my apologies if I have.
But if not, how is there no correlation? One of the, if not the, main reasons why they closed practices after the move to the Rock was because of crowd control issues at the practice rink. I would imagine that they'd have some quality crowd control strategies in place, if they're going to hold a boxing match there.
It is quite simple. During practices at The Rock, there is no security etc working in the practice rink. During the boxing match, there will be plenty of security and arena personnel....
It's not like the practice rink is "off limits" to the public all the time. There are plenty of other hockey games held there when there is security working. The real issue I'm sure is that the team does not want to have to "unnecessarily" pay security so fans can attend practice
I usually don't walk by that way after games but the couple times I did this season there were other things going on at the rink, NJIT games and Rockets practices, so I guess they don't usually have that ice time available anymore.
My guess would be that they make way more $$$ off of the leagues playing games there than they would from the relatively small amount of people that would pay to skate