An answer to the question of whether the Milky Way galaxy is the only one with extraterrestrial intelligent beings will include the same factors which likely limit the number of Milky Way planets with intelligent beings to approximately one.
I said that my QUESS is: one human-level-intelligence per galaxy, on average.
It would explain why our galaxy so far is generating questions like the Fermi Paradox... because WE are the one intelligence in THIS galaxy.
Just my opinion, of course. But I am ever-interested in this issue and always enjoy discussing it.
With regard to red dwarf stars, my GUESS is that almost none of them harbor much in terms of complicated evolution, but I PREDICT that those intelligences (hopefully we are one of them) that do achieve star travel will end up colonizing planets around red dwarf stars, for the simple reason that those are the stars that will still be around — and still be pumping out heat and light — HUNDREDS of billions of years from now.
No one has claimed you said or ask the question which I had raised and then commented on.
Regarding your comment that intelligent beings “will end up colonizing planets around red dwarf stars,” such planets would not have an Earth-like natural environment, although domed communities could be built with an artificial environment.
Another possibility is that a sufficiently advanced intelligence could build a Dyson sphere around the red dwarf, to harness practically all of the energy emitted by that sun for providing environmental conditions in which to live.