The thing is the nomination was his and there was nothing anyone could do about it. He could have stayed in the race. An argument can be made that it looks worse to step down halfway through the campaign instead of fighting till the end. An egocentric guy like Trump would never have stepped down. He would try to turn the base against the RNC and set the party on fire before giving up. That’s the contrast being shown here.
Everybody in his shoes would be at least reluctant. Specially in Biden’s case who is known to overthink big decisions. What matters is that he made the right decision in the end.