Bogle advocates buying broad stock and bond indexes[1], so yes, he's down on gold too. But that doesn't stop Vanguard from offering a precious metals and mining fund [2] or actively managed funds[3].
[1] https://www.npr.org/2015/10/17/436993646/three-investment-gu...
[2] https://personal.vanguard.com/us/funds/snapshot?FundIntExt=I...
[3] https://investor.vanguard.com/mutual-funds/actively-managed