YouTube Brand Account Email Change Query

I am buying a YouTube channel from someone and he has said he will transfer the channel to my email which will take roughly 8 days to do so.
My question is is this process safe or can he still get back access to the channel once it is transferred to me?
He has no problem with me being the only Primary Owner of course we have talked that out but I just have this doubt.
Kindly let me know.

Provided after he makes you primary owner, you remove his own account as owner, i dont think there is anything to be worried about.

I think there is always a chance to dispute it with Google/YouTube. I know this is done on many different sites. As long as you have the original email that was used to create the account it's more likely to get the account back.
If I was you I would not buy it. Let him give you access to the original email and change everything in there.