A big strong shinigami (Urahara) was there to protect his nakama.
Who was unresponsive the last Ichigo had heard from him. Ichigo's trust in the Way of Shinigami must be strong.
He knew something happened in Hueco Mundo but he did not know the severity of the situation. He knew that Soul Society was getting destroyed.
It's not a difficult decision to make. Especially if he has any trust in his Nakama & Urahara.
History shows that while Ichigo does have almost blind faith in Urahara, he doesn't consider the same for the human nakama. Remember, this is the guy who told Sado to pound sand early on in the Arrancar arc, and after being chastised by Rukia (Shinigami!) for being too reckless, he ended up doing the same thing prior to the Hueco Mundo invasion. From that point, onward? Sado was (again!) the first of an Ichigo-led invasion team to lose, and the next time he reunited with Ichigo, it was to hold off fodder. Ichigo returns, and Sado is face-down in unconscious defeat. Ichigo then spent the next eighteen months without his power, and during the process of regaining it, his nakama were (once more!) defeated by the new enemy of the arc, this time being used against their true will to fight him (before being knocked out).
It's definitely not an easy decision to make, but it's clear enough to me that he doesn't have as much faith in them as it's suggested.