We don't alway's pick the fights we end up being responsible for.
And yes, Biden did choose that fight:
Yes, then-Senator Joe Biden voted in favor of the October 2001 Authorization for Use of Military Force (AUMF) that launched the war in Afghanistan
. As part of a 98-0 Senate vote just days after the 9/11 attacks, Biden supported the initial military action. He later opposed the 2009 troop surge
He also chose it when he decided to run for office.