[exim] check_local_user doesn't appear to find LDAP users

This is a spin off of a message I posted earlier:

virtual_user:
driver = accept
check_local_user
local_part_suffix = +* : -*
local_part_suffix_optional
transport = virtual_delivery
cannot_route_message = Unknown user!

...
...
...

# exim -d -bhc xxx.xxx.xxx.xxx
...
...
...
--------> virtual_user router <--------
local_part=jlixfeld.example.ca domain=mail.example.ca
checking for local user
virtual_user router skipped: jlixfeld.example.ca is not a local user
no more routers
----------- end verify ------------
...
...
...

However, the user is in fact a local user (assuming what I think, and
what Exim think are both actually what local users are) :/

# id jlixfeld.example.ca
uid=2000(jlixfeld.example.ca) gid=2001(jlixfeld.example.ca)
groups=2001(jlixfeld.example.ca), 2000(example.ca)
# id -P jlixfeld.example.ca
jlixfeld.example.ca:*:2000:2001::8639924792:-86400:Jason Lixfeld:/usr/
home/example.ca/jlixfeld.example.ca:/usr/local/bin/nologin
#

Is there something I'm missing with regards to how check_local_user
works?