If you read the actual memo (as opposed to the transcription below it), there's no "The". It's interesting that whoever did the transcription put in the definite article, because usage has changed in the last twenty years.
(The memo as a whole, it seems, goes back and forth between "the Internet" and just bare "Internet".)
I actually came to the comments just to talk about this. Not the flip-flop in the article you're pointing out, but I've often wonder when the switch happened in general. Old articles and even TV[1] will use Internet without the definite article. Then, sometime in the mid-late 90's, we started placing 'The' out in front.
My guess would be that techies originally did not use the definite article because other networks existed and had their own names. FidoNet, BITNET, etc. Thus 'Internet' was just a name to distinguish between other networks. Then, as the mainstream population started using Internet and saw that as the sole go-to network, it became 'The' Internet.
(The memo as a whole, it seems, goes back and forth between "the Internet" and just bare "Internet".)