Answer: have a legal question? well, ask to a lawyer. Seriously!

Call a reputable lawyer, don’t trust information/advice/speculation from a website.

If you serious in using this code for commercial purposes, better to get a paid consultation. Otherwise, you may risk the future of your product as well the company. Law suits are serious matters.

IANAL

Well, it’s a risk you shouldn’t take: he’s agreed once to license the code under LGPL, so him relicensing his code might be a violation of his agreement with Google, not with you.

Which in turn means, you probably can’t do a lot. You can contact him and request more information (in multiple channels, if you have to) and, if he tries to tell you that the code is not LGPL, you could report this project to Google.
I don’t really think this would help much. If it’s not an honest mistake he’s made, he will probably pull his code off Google Code and publish it somewhere else, while you’re left with a bad aftertaste.

Another thing – he might not be ignoring you, his email server might just be throwing your mails to SPAM/Trash and he could be totally oblivious about it. So you might try to repeat or use a different communication channel (IRC is common for open-source), if there’s a PM function in Google Code, try this as well, etc.

Bottom point: You can’t rely on using his code under LGPL, unless you get a good confirmation from him that the license is indeed LGPL.

Also, make sure to talk to a lawyer about this stuff – don’t trust some strangers, potentially half a world away, in an entirely different jurisdiction to give you advice on these topics. Heck, even professional lawyers sometimes have difficulties answering FOSS licensing questions… If answers in this site had tags, IANAL would have been the top one.

The author has released the code under unclear licensing terms; you need a lawyer if you want anything conclusive (and even then, it may be so unclear that the case has to be presented to a judge or jury to really clear things up, which means a lawsuit, which means you can lose a truckload of money). It may be that restrictions from both licensing agreements apply, or it could be that you get to choose which one applies, or that one of them is void and the other applies, it may depend on how you acquire the code, etc. etc. Just too many uncertainties for a non-lawyer to oversee.

Legalities aside; in my experience, a project released under such vague circumstances is a big red flag: the maintainers are obviously unwilling to put even minimal care and effort into their licensing model (really, it’s not hard at all – just find a good list of OSS licenses and pick the one that fits your philosophy), and it is quite likely that the rest of the project is comparably sloppy. Project maintainers that care about doing things the right way, having clean code and project structures, and making it ridiculously easy to use their work, tend to be equally religious about licensing. It doesn’t have to be that way, but I’ve found it to be a quite accurate assessment most of the time.

IANAL

As far as I know the GPL and LGPL licenses are largely “take it or leave it” licenses, you can’t change the license and still call it the GPL or LGPL. If you license something under the LGPL the author cannot then say you can’t use it for commercial use. The GPL clearly states “You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee.”

First of all check with the author if it is licensed under the LGPL (you don’t mention a version number) or not, also ask him about the exceptions he is trying to make.

If the author still tries to claim both licensing under the LGPL and “not for commercial use” you may decide if you want to email GNU (originators of the GPL) and / or the Free Software Foundation. One or the other of these may choose the explain the realities of the LGPL to the author (or not).