"So?" - No - Sue.
1) They can easily argue that it was not known that it was stolen
2) Who cares, they didn't damage it.
3) They again can easily argue that they needed to verify it was a legit Apple product first. There were reports during the week that it was a Chinese fake.
4) So?
5) Again, So? They asked for a formal request so they could have a record of the request instead of just a phone conversation. Not a big deal.
Apple isn't going to do anything other than possibly change their policies regarding who/how products can be taken off campus in the future.
Suing Gizmodo or the guy who found it would not be in Apple's best interest at this point. The information is out there and can't be taken back with a lawsuit. Its done. They are getting a huge amount of press over this. While it might not be the way that Steve would want to introduce the phone to the world, its still publicity. Lastly, if it is shown that the guy had an open ticket with Apple and had tried repeatedly to get in touch with someone at Apple, no judge is going to throw him in jail....please. Suing would just be BAD press for apple.
I don't know whether it would be in Apple's best interest to sue or not, but it is certainly in the best interest of the People of California for the District Attorney to prosecute felonies - especially when they are publicly confessed.
To answer your points above briefly:
1. They cannot argue that they didn't know it was stolen. Why not? Because they admitted on their website that they knew it was found in a bar, that they recognized it as a prototype, and that they had so much confidence of its provenance that they were willing to pay 15 times the market value for a new, not lost in a bar, iPhone.
2. Who cares, they didn't damage it. How does that defense work for a car thief after the car is recovered without a scratch. Or for the trespasser who breaks into your house, but only watches TV. And, by the way, if you actually took a moment to look at the Gizmodo site - they DID damage it. They took it apart. If you or I did that to our purchased iPhones - guess what - the warranty would be voided.
3. They can't easily argue that they needed to take it apart to verify. Especially when they could have taken it back to the bar (investigative reporters that they are) and found out in 2 seconds that the poor Apple tech had been calling non-stop to find it. If your point were correct, you could also "easily" argue that to verify whose Porsche keys you found in a bar, you had to go to the parking lot, open the only Porsche in the lot, take it around for a spin, and disassemble it in your garage to determine who owns it.
4. They profited - you say "so?" How about I find the final draft of the novel you've been working on for 4 years in a bar. How about you copyrighted the material you wrote. How about I publish your novel for all to see and make money off of it? Haven't I deprived you of at least some sales? Haven't I unjustly enriched myself? So?!?
5. Nothing wrong with asking for a formal request. But it begs the question of why they didn't ask before they purchased it, ripped it open and published confidential information. Moreover, they had no right to the device in the first place. Give it to the police - wait 6 months - it's yours.
Would you have less sympathy if it was the publisher of Motor Trend Magazine who acquired an unreleased BMW concept car from someone who "found" the car on the side of the road? Would you keep saying "so what?" or would you think that Motor Trend was guilty of Grand Theft Auto?