There are two issues: client side and server side. On the client side thread safety can be an issue. PG lib is threadsafe for a subset of operations (in particular those I need for the AOLserver driver) but not all (and unfortunately I've not tracked the "when is it, when isn't it?" issue beyond the needs of the AOLserver driver).
If the guy embedding this language felt that this indicated problems with thread-safety on the server side, he's wrong.
On the other hand, if he's providing client as well as server side services then he needs to make sure he's calling the thread-safe subset of PG lib.
My guess, though, is that he's muddling potential issues on the client side with the restrictions placed on server-side embedded languages.
