I think it was to make sure that there was a clean break of the data from the timeline just in case Control had hidden some part of itself somewhere. That way the data was in no danger of being found while efforts were made in present time to ensure there would never be a “Control” again. Georgiou said she leaves as little to chance as she can (I’m paraphrasing a bit there). Notice she didn’t say Control was “dead” or “gone”, she said “neutralized.” By still flinging Discovery far into the future, I’m guessing Pike and Saru felt the same - this was too important to leave to chance, they had to be sure.