tlhIngan maH taHjaj is (a) a slogan, and (b) not canonical. As a slogan, it's not going to be careful to ensure everyone knows what the antecedent of its elided pronouns are. As a non-canonical sentence, it's not a data point in what can and cannot be said.

Once in a while, I think to myself “hey, it could also be parsed as {tlhIngan maHtaHjaj}!”. Then I remember that {-jaj} isn’t supposed to be combined with an aspect suffix (even though it sometimes apparently is). Then I forget again, and the cycle starts anew.

HevetlhDaq maw'chu'ghach tu'lu'.

-- 
SuStel
http://trimboli.name