My response is that the upward query, and the t=s flag (which provides a
way to limit the application of ASP outside the immediate domain) are
not intended to cover subdomains. Rather, they provide a way to cover
terminal leaf nodes within the domain (e.g., hostnames) that can be used
as domains (in the 2822 sense) in email addresses.
In an IM discussion, Eric pointed out that the current text for the
"t=s" flag confuses this, because it says, "...named domain, and not to
subdomains." This should probably read, "...named domain, and not to
terminal nodes (e.g., hostnames) within the named domain."
NOTE WELL: This list operates according to