Ichigo does have twice the power of a captain in normal mode. He's always let ichigo run around fighting battles so ignoring ichigo being in danger isn't out of character due to his general confidence about Ichigo's power. Ichigo is the main character of a shonen manga with a girlfriend capable of defeating death itself through the power of denial. How much safer can he get?
Even assuming Azien and company gets past the entire military force that soul society+vizards brings forth(which he knew about before everyone else due to being friends with sandalhat) they'd be weakened or half dead from the battle and easily picked off. He also has a penchant for random sneak attacks if you remember all the dynamic entries from Ichigo's home life so it would be quite possible nor out of character for him to outright gut Aizen as he walks through the door before any of that hypnosis shit.
Given how shonen manga operates he's quite possibly up there with Kenpachi or above in power too while having centuries more experience. The longer it takes for a character to showup as important or fight the stronger they are generally. So yes arrancar aizen gin and tousen= not a threat,
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