Mind you, I'm not suggesting that the piracy be ignored...
If Marc ends up selling books in today's environment, you can bet that someone will take that book to a print shop, break the binding, and take the time to scan in the material to their computer. Today, it isn't all that hard to do a web search on torrents for books. Not too long ago, I noted that someone had made a PDF copy of GURPS CYBERPUNK. I had considered blowing the person in, and ultimately, I just ignored the situation on the grounds that I don't give a rat's butt - I should, but I'm not all too keen about SJGames these days. Later on, when I had reconsidered my indifference enough to maybe share the info, I forgot precisely WHERE I had located the illegit copy. If it isn't out there easily accessible, then it cuts down on how often the copy will be disseminated.
None the less, the question becomes one of whether or not the sellers of legit PDFs are making enough money despite the piracy. I'd dare to wager the following:
Those who really CARE about Traveller, won't be involved in the Piracy. Those who don't care about Traveller will probably not care about the act of Intellectual piracy, but on the second hand, probably won't play the game all that much if at all, and let the pirated copy languish on their hard drive taking up space as it were. However - those who end up not caring initially about Traveller, and become hooked on a pirated copy, will also probably be like the rest of us dudes... they will wait with eagerness for the next NEW installment to come out, and being the impatient sods they are, actually PAY for the copy to enjoy the priveledge of having it faster.
Net effect? Perhaps (note: I say perhaps) a little extra in sales. If they weren't going to buy a legit copy to begin with, they'd not have been exposed to Traveller. Result: No sales. If they are the type who just take what they can and act smug about it - and will always do so, then perhaps those they play WITH will become ensnared in the joy of the hobby and expand sales that way. To be sure, there will be those who pirate a copy, give it to their friends, and they in turn won't need to buy a legit copy. Chances are however, that they would never have purchased a copy otherwise. At least with the pirated copy, there is a chance at enticing others to become card carrying travellers
All in all, I don't have it inside me to muster up the raw outrage at the piracy. If it became widespread enough that Marc were to give up on Traveller all together, or that other companies were going bankrupt - then yeah, I'd be unhappy. I just don't think it has hit those levels as yet.