It looks like you don't understand the difference between sacrificing himself for others, and having the ability to defeat.
- Rayleigh was willing to fight BB, if he BB decided to fight him and Hancock, he admitted he would lose.
- That doesn't mean Rayleigh would want to fight BB if BB doesn't attack his friends.
Same thing as Shanks, he is willing to fight BB, IF only he needs to sacrifice himself for his friends.
You seriously arguing Shanks wanted to fight BB but he couldn't find him anywhere in 1 year?