Attempting to back Bitcoin with gold would be like trying to back gold with silver. The bitcoin doesn’t need any help in the value department.
Yes it's total nonsense. You can always ask: What's backing gold? And then you will come to the conclusion, that gold is backed by nothing else than the effort needed to extract it from rocks. Creating bitcoin requires effort (energy), too. So bitcoin mining perfectly resembles gold mining on a virtual level (hence the term "mining" is used).
The concept of backing only makes sense when you have items like paper money that you want to have high trade value but that do not need much effort to create.
Bitcoin is unlike fiat money that can be created at will. So Bitcoin does not need backing.
Bitcoin is sound money like gold.