[vulf]

It's not throwing him under the bus. It's distancing him from the investigation. That's both to protect him, in case things favor his story, and to protect the company, if it turns out he was in the wrong.

In both cases, they wouldn't want him having any potential influence on the investigation. To do that, his power within the company needs to be suspended until a conclusion is reached. The parties investigating (likely HR and the other founders) must be able to do their job without fear of retaliation from the accused founder, that would taint the decision.