The section "Sanitization" talks about what needs to be done to safely display user submitted content, which doesn't actually have anything to do with "Input Validation", despite being a part of that chapter.
Having this section in the wrong place can mislead developers and give them a false sense of security ("I don't need to worry about XSS, because I've removed the HTML stuff").
I suggest moving the "Sanitization" section to the "Output Encoding" chapter, probably renaming it to something like "HTML".
The section "Sanitization" talks about what needs to be done to safely display user submitted content, which doesn't actually have anything to do with "Input Validation", despite being a part of that chapter.
Having this section in the wrong place can mislead developers and give them a false sense of security ("I don't need to worry about XSS, because I've removed the HTML stuff").
I suggest moving the "Sanitization" section to the "Output Encoding" chapter, probably renaming it to something like "HTML".