This should be structured as adding some requirement to the doc, but it's not. Confidentiality is optional. The ability to provide confidentiality protection regardless of bindings is the issue here. The next issue tries to capture this but goes into too much detail. Each binding must include a description of how the confidentiality and integrity of SAML messages can be protected within that binding.
Deployments can choose the appropriate solution.
This is certainly an issue that the TC has to decide, but it doesn't seem to me to be a UseCase-Requirements issue. How this is achieved via bindings and new SAML formats is part of the engineering effort. These are statements about engineering decisions, not about requirements. These are statements about engineering decisions, not about requirements.