FCE 3.5 is a universal application. However there is a bug in its installer app that triggers the PowerPC dialog box, even though it is also universal.
The two existing workarounds are either to use Pacifist or a method using Terminal, developed by Jeremy Johnstone, Jeremy has also developed a simple fix using TextEdit and I am waiting for further instruction from him so I can repeat that method here.
He has generally described the problem and its solution, but since I do not have a copy of FCE 3.5 readily available to me, I have no way to determine if my interpretation of his description works correctly. I am loathe to post a "fix" that I have not successfully used myself.
I considered purchasing a copy of FCE off of eBay, but the prices it still commands are just too high for a simple philantropic project. A "loaned" copy of FCE 3.5 (or FCP 6, which also suffers from the same installation bug) would facilitate matters...