Take things you read on a forum on the internet with a mountain of salt. Not to detract from any posters here, but anyone can say they "know someone" at any company in any industry.
Bottom line is, the car is months away from production and still a prototype. There are several prototypes in fact, and the weight of one may very well be more or less than another.
So who knows the truth? No one.
If you can, wait until the car comes out to say whatever you want about it. You can talk about features you see in pictures, but you can't weigh pictures and can't trust what someone says about a car that isn't even available yet.