If he *DID* use an In Circuit Programmer, he wouldn't have had to solder the write-enable points as the ICP would have tied those pins high.
I really think he used a 007/mechassault exploit, but you didn't notice him whack in the game disk.
Really, all this talk of TSOP removal and ICP's ignore the fact that it is only a simple job to do a TSOP flash, so why would anyone make things difficult? At the end of the day, your modder provided you with a modified xbox at a price which is not unreasonable for a house call.
Perhaps your modder didn't communicate effectively with you (language difficulties?) in regard to what he was doing, but on the other hand you didn't question him either.
You have plenty of offers to put an actual modchip in your box at a reasonable price (and I'll add to the list. $80 installed for an Aladdin, and I'll revert your TSOP to stock. See
www.meltonmods.com) so if it bothers you that much, fix it.