Green Infrastructure Stormwater Reuse

This is not a GI practice. The intent of GI is to mimic the natural hydrology. Removing all infiltration, evaporation, and evapotranspiration does not do that as it modifies the base flow. 

Is the answer to your question below, No?

"The definitions of green infrastructure and low impact development strategies appear to exclude capturing roof rainwater for reuse within the building for toilet flushing, irrigation, cooling tower makeup, etc.  Is it really true that capturing and reusing the water within the building will not help earn this credit because it's not a strategy that mimics the site’s natural pre-development hydrology?  Isn't much of the point of this credit to significantly reduce or eliminate stormwater runoff from the site by any means?"

Capture and reuse for process mechanical and plumbing has been repeatedly denied. There are a bunch of examples in this forum. 

A colleague of mine here in Sweden has done the flushing of toilets with rainwater in a couple of projects and earned the rainwater credit and the indoor water credit after getting this response (part of it) from LEED Coaches a couple of years back: “It should be noted that while captured rainwater may be used towards both irrigation and flushing toilets as a Rainwater Management strategy, and rainwater may help contribute towards earning the Outdoor Water Use Reduction and Indoor Water Use Reduction credits, rainwater cannot be used to help contribute towards earning the Outdoor Water Use Reduction and Indoor Water Use Reduction prerequisites.” I have not done it in my own Projects so far...