Do tuple and union need to be reserved function names?

In section A.3 (Reserved Function Names) of the XPath 4.0 and XQuery 4.0
draft specifications, the tuple and union keywords have been added.

I don't think these (or more accurately, the keywords for the new item type
constructs) are needed, as they cannot currently be used in places where
functions can. Only KindTests can appear as path expressions, and the only
other reserved names should be for other types of expression (if, switch,
typeswitch, etc.).

From a similar reasoning, the following keywords should be able to be
removed from the list as they are also only ItemTypes/SequenceTypes:
1. array
2. empty-sequence
3. map

Kind regards,
Reece