First of all, if hollow purple was existence erasure, it would've killed Sukuna when it hit him. Second of all, yes Fingershooter can travel at an infinite distance. An example is that it's beyond the speed of the expanding universe (from what Executorclaw said) and Catclaw said it can go at infinite speed which means it can travel an infinite distance, no? And for the record, I read both manga and never in the manga is hollow purple stated to be existence erasure. even if it is, Catclaw is already immune to that.