I wonder how important what the characters say is compared to what they do-- and the importance may be in what the readers remember.

Card has an actual genocide.

In ST, Heinlein speaks in favor of crude "roll over the other guys so that your genes can survive" expansionism, but he portrays a society where racial/ethnic background doesn't matter for humans, and an ongoing war which won't necessarily end with the Bugs or the humans being wiped out.