I don't know to what extent "mainstream" EA can rest on Singer's plaudits: I got a decent amount of pushback from EAs (or EA-sympathetic people) on this site just last week for pointing out that they've diverged significantly from Singer's original altruistic positions.
It seems a little hypocritical to use him as ethical cover without adhering more closely to his specific ethical proscriptions (which don't, to my knowledge, include Internet Rationalist stuff like AGI and colonizing the galaxy).