Phileas

I tried to book SYD-PEK-IAH-CLE-YUL along with a return YUL-SYD (this one under mpm).
First agent I talked to told me that it does not work because it is way over the mpm and this is the only rule that counts. According to her, there was no such thing as published routings. Oh well...
Second agent was more open to checking the existing rule and as a matter of fact, there is a published routing by CA:
The agent confirmed that SYD-PEK-IAH-YUL was a valid routing but adding CLE was not allowed because it is not mentioned in the list of allowed airports. Is that correct? For the NA part of a routing rule, are possible airports limited the ones listed in the rule?