Alden made a case for them having made poor choices driven by panicked impulse, and though Rick didn’t pinky-swear to bring any stragglers back to show them the error of their ways, he technically agreed.
And then later broke that promise in some pretty horrifying ways that also didn’t do much for Rick’s moral standing with Michonne.
Viewers knew bloodshed was imminent once Rick chatted up Alden, the poster child for Hilltop rehabilitation, who very specifically requested for Rick’s mercy where the other Saviors were concerned.
Because Rick is currently unable to just sit serenely for any measurable span of time without getting overwhelmed by grief, he tasked himself with tracking down the escaped Hilltop prisoners.