The classic Defenders logo certainly has a much more retro appearance than the current Defenders logo from the Netflix series, so it’s understandable why the classic logo was chosen over the current one.
Despite not appearing in Avengers: Infinity War at all, Marvel’s Defenders still managed to get at least a slight nod in the latest Marvel movie.
However, the reference was moreso a reference to the Defenders from the comics than the Defenders from the Netflix series.
Considering how enormous of a comic-book movie event Infinity War was, it is completely understandable that it managed to include a great number of Easter Eggs and cameos.