[NTG-context] context.delayed is incompatible with some functions

Dear List, I was reading Typesetting in Lua using LuaTEX https://www.ntg.nl/maps/41/11.pdf. By playing with the examples in the article, I found that `context.chapter(context.delayed("one"))` does not render the delayed text properly, while `context.bf(context.delayed("one"))` does. I would like to ask whether this difference is by design and, if not, whether there is any systematic way of giving delayed arguments to `context.chapter`, where by "systematic way" I'm referring to a proper use of the existing definition of "\chapter" instead of any faked duplication of it that visually resembles a chapter title. Thanks in advance. Best, Sylvain