I know Dan, I picked up a Jungle King a year ago off him. Really nice guy, with some really nice restored games.
The posting clearly states that you can use it for whatever nefarious purpose you want - he even states 'MAME' in his message.
And I agree with Rampy that the newsgroup messages are in a public forum, and can be acted upon by anyone. Whether or not whoever is giving the cabinet away will give it to you or not is their choice.
I've also emailed Dan about the cabinet. Not sure if I'm going to do anything about it, I've already got one project cabinet going, one in the queue, and one at my mom's garage that I'm not sure what I'm going to do with (it's a completely stripped Jungle King)