Science has long established friendship as a distinctly human-human interaction consisting only of the purest non-incentivized intentions.
Of course one could define "friendship" in a way that only human friendship qualifies, but that is certainly not the common definition.
We have three dogs and three cats, and every day I see behavior and interactions among them that I can only describe as friendship. Yes, between the cats and the dogs too. I think anyone watching them would call them friends, at least by any everyday meaning of the word. [2]
Scientists don't get to redefine a word that means something else in common discourse. That's not how language works. Next thing you know, they will say Pluto is not a planet!
Oops, they did, some scientists anyway. But not the science team that sent New Horizons there and brought back better pictures and more information than we ever had before. They call it a planet. [3]
[1] https://en.wikipedia.org/wiki/No_true_Scotsman
[2] https://en.wikipedia.org/wiki/Friendship#In_animals
[3] https://www.scientificamerican.com/article/pluto-rsquo-s-sec... (Full article is behind a paywall, but the subtitle has the relevant quote.)