it is valid collateral. it's much more valuable than the loan.
How it can be more valuable than the loan? Will lender be able to sell the channel by 1000$. What will be done by the channel that its value will be more than 1000$?
I think it is like an old t-shirt with which you might have some memory so that might be too much precious to you but that has no value to others. Because:
1. The new owner will not take payment for Adsense as you are the owner of the Adsense.
2. If the owner change Adsense then youtube/google suspend the account or ask for verification as info has been changed.
3. You can report that the account has been hacked.
4. you can report that the account has been bought.
5. your content and the new owner's content will not be the same so his income will not be good.
6. And many more.