[synchronise]

Well the author could always append AGPLv3 licenses to all of his original code. The parts that he integrated from MicropolisJS would still remain licensed under the GPLv3, but the greater work and resulting binaries would be licensed under the AGPLv3.

[__david__]

True, they could do that. Your original comment said "recourse", as if it would be bad to take GPL code and integrate it into a AGPL project. Which is also part of the reason I don't understand your question—Why would one need any recourse when someone else is abiding by the terms of a license?