A mucgh better alternative for immediately eliminating enemy fleet ships is the Maw, a few of those things will easily eat up dozens of enemies (depending on how long the battle lasts) and even Mk Is will work against any enemy (no mark limit to what they can eat and the capacity doesn't come into play usually since most battles are over long before the Maw is full, the highest values I've seen on mid caps was in the twenties).
There is no doubt the Maw is a better choice. (Except when the AI pops one and suddenly you have another 50+ ships sitting in the middle of your blob, which tend to pop more maws) But it is only a choice when you get lucky with an ARS or pick it at the opening of the game. The Ion Blaster is available every game that spire craft are enabled, it should at least be a viable choice to build
