> The FSF have actual copyright lawyers on hand. Where have they said this?
It is part of the official GPL FAQ [0].
Does the GPL have different requirements for statically vs dynamically linked modules with a covered work? (#GPLStaticVsDynamic)
No. Linking a GPL covered work statically or dynamically with other modules is making a combined work based on the GPL covered work. Thus, the terms and conditions of the GNU General Public License cover the whole combination. [...]
> The example is not very easy to understand. In general copyright law isn't really applicable to your own right to distribute your own original work.
The very question is if my work is original. If I create a program that only works when (dynamically) linked with a (GPL) library, is my program an original work, or is it a derived work of that (GPL) library? This is a question that has not really been settled in court; the official opinion of the FSF is clear: it is a derived work.
If the explicit question in the GPL FAQ is not engouth, note again that the whole purpose of the LGPL (and other GPL+exemptions licenses, such as Java's and GCC's) when compared to the GPL is to allow this type of use, which they clearly would not have created unless they believe it would not be allowed for a full GPL library.
The FSF have actual copyright lawyers on hand. Where have they said this?
The example is not very easy to understand. In general copyright law isn't really applicable to your own right to distribute your own original work.