IPhone :: Did Genius Bar Brick My 4 With 3rd Party Unlock App

US Apple Employee took my Japan iPhone, tried to unlock my iPhone by installing an app called "unlockit.co.nz", put my AT&T sim card in, read FAILED, and said it didn't work. He reassured me that my Japan iPhone will still work when I go back there, but I have no reassurance now. Did they mess up my iPhone and not taking responsiblity for it? Do Apple employees typically install sketchy 3rd party unlock apps that change APNs?

I went into the Apple Store today with both my US iPhone 4 (16 GB Black) and my Japan iPhone 4 (16 GB Black). My US iPhone was having issues with its bluetooth and home button is sticking a lot. He couldn't replace it since it was out of warranty and suggested that I find a 3rd party repair shop or look on Craigslist.

My Japan iPhone 4 is still under warranty and suffers from one spot on the screen being exceptionally bright. He said he could replace my Japan iPhone with a US AT&T iPhone. I told him, I'm not sure if that would be smart since my Japanese Softbank SIM card may not work anymore in an AT&T iPhone. He explained to me how unlocking works and said he can easily set it up for me. He took my Japanese iPhone, went to some site, installed a program, did a few things, and took my AT&T SIM Card out and put it into my " newly unlocked" Japan iPhone. The phone kept saying SIM Failed and he restarted it, and it still didn't work. He put my AT&T SIM card back into my US iPhone and thankfully, it still read my SIM Card.

He offered to exchange my Japan iPhone for a US iPhone 4, and suggested that I call AT&T to have them unlock my phone for me. He said they would do it, if I was out of contract with AT&T, but I wasn't, so I went home back at status quo, or so I thought.

I looked at my Japan iPhone again, and noticed that there was an app called, "unlockit.co.nz". It opens up Safari and pulls up something called APN Changer. Upon closer inspection, it's the same app/site the Apple Tech pulled up when I was at the store. I'm a bit leary about odd apps, especially apps that originated from the domain co.nz. I googled the site and looked it up, and it seems a bit odd.

Now, I don't know what this program exactly does, but I'm a bit annoyed that I don't know what app the Apple Employee installed and what it exactly did. I have no assurance that my Japan iPhone will work in Japan now after he installed this app and did something. Is it the Apple policy to go and install 3rd party apps? Will my Japan iPhone still be good when I go back or am I going to land in Japan and spend the first few hours at an Apple store trying to get my phone replaced/fixed?

Info:
iPhone 4, iOS 5.1