Which competitors? The J-20 or SU-57? Yeah, I wonder why those wouldn't be selected.
In the fickle Brazilian political environment, not aligning with the US might end up being a rather pragmatic move. As a politician, who knows how badly your successor will fuck up those ties?
Buying the _eurofighter_ wouldn't let them share the same platform as the _rest of Europe_? I realize that the F-35 has racked up a number of sales recently, but there's quite a few eurofighters around still, and more on the way IIRC