Seems perfectly reasonable to me. Remember Grimgnaw from Neverwinter Nights?Would it be against a monk's alignment if it were a mercenary for hire or an enforcer for some shadowy organization like the shadow thieves?
How would that work in the world?
A Mercenary could hire out services for payment other than money. Upholding an ideal, or simply taking opportunities to prove and test one's strength could both be strong motivations for a Monk Merc.a LN merc monk could be interesting..maybe the order keeps the good/evil balance in check and hires out to one side or the other..depending on who appears stronger
Lawful Evil is the best alignment to be in D&D. Makes sense that a Monk can be LE.![]()

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.