Hannibal King said:spreading disease is evil and not something a lawful character would do.
Note that these are two completely different things. I am not sure if you meant it as a continuation or as a seperate thought.
I can see someone making the arguement that it is not a 'lawful' act, but saying it is a 'chaotic' act seems like a stretch.
It is evil to cause suffering, and diseases definately cause suffering.
Hannibal King said:anyone can argue that killing an innocent child is a lawful good act if it serves the greater good
Killing someone for the greater good tends to go on the evil side as well. Lesser of two evils and all that.
If you kill an innocent that is evil. One could argue about its lawful or chaotic nature (depending this could go either way) but it is definately evil. No way around that.
Unless the character does something directly chaotic with these guantlets I certainly see nothing to make him lose his monk status.
If anything, they sound 'perfect' for an order of monks whose goal is to spread plague across the land in order to bring some sort of odd order to everything. I believe there was a monk somewhat like this in NWN actually.