Unfortunately, you've got some out of date information. Males do fine with other males, provided they're given a large enough cage, and their genetic background or temperament is not really necessary to know before bonding them.
It's nearly impossible to predict how one pig will react to another. I'd recommend telling your friend about Guinea Pig Cages website (that Sasami linked) and then contacting one of the local small animal rescues for help with 'dating' so that your friend's pig can find a buddy.
Neutering isn't impossible, and most males do fine with it, but it's not necessary to pair them with a female to insure they'll get along (in fact, I've had multiple male/female and female/female pairs also fail numerous introductions).
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry