The only proof you have that that is a Bothan is that it looks a bit like some of the EU descriptions.
Even if it's official (which it isn't http://starwars.wikia.com/wiki/Holwuff ) it's never mentioned.
The audience of ROTJ would not connect that image (which you have had to blow up and point out with a red arrow) with the moment of forced sadness in the the final film.