Please learn what FHS is and how it fits in here. Seriously. Anything that is packaged for a distribution on a regular desktop GNU/Linux system DOES NOT belong in /opt /opt itself is mostly a historical feature or used by anything that can't/won't be packaged(think proprietary software like DB2, Oracle etc...). Yes I am well aware of what /opt on maemo does but it doesn't mean I agree with it. As for /usr/local... yes it's there for things an admin would install... but in this case it could be abused. Also looking at other systems like BSDs /usr/local is where their packages install by default. Most things out of /usr/local are part of the core system. And this would probably fit maemo more as it would be more true.
Maemo is NOT a regular desktop system, even though I wish it was more similar... There is no authority which can enforce the FHS. It's just a guideline.