I`m not 100% sure, if I got your point correctly. I guess, you should look at the following paragraph:
"You can also use a weapon with which you have
proficiency as an implement. When wielding the
weapon as an implement, the weapon's character
istics-proficiency bonus, damage die, and weapon
properties like defensive or high crit-are irrelevant to
your implement powers." (quoted from PHB 3, p.64)
So, it is basically up to you to describe it whether your monk kicks the crap out of the baddies or if her prefers to stab them with his prolongated kitchen knife. The rules aren`t clear about the use of weapons and monk attacks, i.e. if you use your weapon to attack while you still kick and punch him or if the damage and the effects rélated to the the power are the result of your weapon usage.
That is how far I can agree with drothgery, but it also states that properties granted by magic wepons do not apply to monk implement powers. Either there is an erratum I haven`t seen yet* or I have to correct Drothgery at this point.
At last, regarding your question, I have never found any evidence proving one or the other theory. Maybe the wizards have already released a statement in the Dragon Magazines, but since I´m no subscriber I can`t tell. So, if anyone should know better, go ahead and correct me.
Maybe one could argue that due to the fact that your weapons characteristics do not apply the monk simply wields his weapons for defensive use (so long as you do not use the Crushing Tempest Style or the like, in which case I would argue you defintely use your weapon to attack since otherwise there would be no need for the requirement line).
It`s simply a grey area due to sub-optimal wording. I hope this still helps to resolve your arguement.
*due to the fact I have never played or DMed a monk this is actually quite possible