It's a branding issue, they want the sponsor to stand out. When you put the opposite colour as a border on black or white text it doesn't stand out well against the black and white stripes. You could double border the text, say it was black text you then do a thin white border then a thin black border on the outside. The only thing to do would be to cut the stripe design short on the jersey itself around the sponsor logo, but I get the feeling with adidas that they just make a jersey and then you do what you want with it in terms of sponsor placements once the design is confirmed.
On Olympiacos' kit they've gone with a double bordered logo, but see how it blends into the shirt.