Worst case scenario, this gets immediately parasited and it's the sentry equivalent of an Ice Wall or Quandary. 2 credits really isn't that bad, and you end up breaking even with the runner which is pretty good for a piece of ICE anyway.
Best case, this could have a ludicrous amount of subs that makes breaking it repeatedly a massive tax. For example, Gagarin or Industrial Genomics. You don't want to access/trash all their assets, but not doing so is going to make them money and make this a massive obstacle.
You could click for credits for five-hundred years and not have enough to pay all my subs.