It was explained in the thread regarding last week's test why the test net was not used - doing so would not properly measure economic incentives of both miners and other users in regards to TX fees.
BS. If the attacker had a tenth of a clue, she could easily simulate all transactions over a period, and add his spam to that.
Do you read and store all your email spam as well, forwarding copies to all your friends?
You are comparing apples to oranges. Email I receive to my private email, is by definition private and will not (with very few exceptions) be shared with anyone.
But you do read and store it? No filtering of any kind? Treat all mail alike? I am sure the spammers won't mind if you share it, btw.
A better analogy would be would I forward emails sent to my mail server intended for my customers when the sender is paying for them to be forwarded? The answer would obviously be yes.
So you take money for spammers to spam your customers. Great. I am sure you get a lot of them. Do your customers know?
Eligius is treating certain inputs differently then other inputs. Plain and simple. They are saying that Bitcoin owned by one entity is not allowed to have their transactions confirmed by their found blocks.
Nope. They didn't say that. Even when you download and install a fresh Bitcoin Core form bitcoin.org or compile one from git, there are anti-DoS measures preventing most spammy transactions from getting forwarded and mined, and it prioritize non-spammy transactions over spam. This malicious attacker has tweaked his spam to get around the default anti DoS measures. Nobody can prevent miners to tweak the anti spam code in their server to ignore the new spam transactions or change the priorities. In fact, they don't need to mine any transactions at all, or they can choose to mine all transactions. Most miners are bitcoin friendly however. They keep keep the anti-DoS measures, include all sensible transactions waiting to get mined in their blocks and only mine spam if it doesn't get in the way. All miners prioritize sane transactions when blocks are full.
This is not the first time that eligius (via Luke-jr) has done something similar to harm Bitcoin. Gambling sites were previously blacklisted by default by mining software when this was pretty clearly not a wanted "feature" of such software. In other words the software did things that its users did not want. This is how a lot of people describe malware.
I am a user. I want this. I want bitcoin to be successfull, not spammed to death.