I see, however, that you've place a seemingly arbitrary restriction on using core modules

Actually, he placed a seemingly arbitrary restriction on using non-core modules. Some may argue that that's more understandable... but then one wonders whether he would be allowed to write a module himself and install it. Once you realize that you could just copy and paste code into your program, restrictions like that do indeed seem arbitrary, at least when simply toolsmithing. They do make sense, however, when creating an application for commercial distribution where you may be trying to avoid licensing pollution, reduce footprint, and/or ease installation.

-sauoq
"My two cents aren't worth a dime.";