Y'know, I'm surprised that some folks are confused why old Judges Guild stuff can still be bought/sold vs the newer PDF versions of stuff can be pulled and barred from sale.
Of course, what I'm about to say does not allow for any Judges Guild Traveller material being available for purchase as a PDF. Didn't find any but I don't know everything.
Anyway, once a physical product is legally released for sale, pretty much no one can stop the endless resale of that product (barring like proof a particular copy was stolen, offered for sale against the terms of the publisher etc.). Once it's sold it's out in the market. The thing about "against the terms of the publisher" I gained experience with while working for AEG. Their Cust Svc manager had authority on eBay to kill auctions of their products and report it for dispute to the powers-that-be on eBay.
The items he could do that with are like prize/participation items for an event that was explicitly scheduled for a certain date but were for sale before the event could be held. Anyone who signed up to get these materials were under an agreement to follow the enclosed rules and the publicly published dates. In one case a store trying to sell a complete prize kit after the event was stopped. Why? because the store reported the event went had X number of players etc but the kit was complete. Had the event actually happened as reported they could not have a complete kit.
PDFs are like physical product that went out to distributors and stores, and for some reason the company recalled the products. They can't get back what customers already bought but everything else is no longer for sale. Heck, under 3.x D&D WotC really hurt one company when it said the entire run for two of that company's books had to be pulped because they used Greyhawk specific info (deities) from the PHB and that info is not in the SRD for use.
Early this year WotC cancelled all sales and downloading of the entire line of books for 4th ed D&D. DriveThru RPG, Paizo Publishing, etc. had to terminate customer's ability to re-download the PDFs they had already purchased because of the nature of WotC's license for the sites to sell the PDFs
It's a publisher's right to say "no mas, no mas" on the sale of something.
I don't know what happened with the 1248 stuff but hey, that's how business is some times.