Oh brother.
Call it splitting hairs, whatever, but it's basic business 101. In fact, the customer service and management training material that Disney themselves teach discusses, in depth, what it means to be "family friendly." I think it's "Be Our Guest: Perfecting the Art of Customer Service" by the folks at TDI or maybe "The Wonderful World of Customer Service" has a whole huge section of the book that is devoted to addressing the whole "family friendly" aspect of their services.
The fact is definition of "family friendly" (by most people in a business world, but more importantly without a doubt Disney since Walt talked about it when creating the park and it's the mantra of the park now) is that the overall theme, service, experience offered, as well as the level of safety, is suitable and accomidates the needs for all members of your family without exception. And by family, one means people, not your dog, your goldfish, your favorite stuffed animal, your beloved houseplant, or whatever random factor it is you wish to include in there as "family." The goal of the park through their model of meeting the needs of guests (safety, courtesy, showmanship, and efficiency) is that the park as a whole is "family friendly," as in it is something that, overall, has offerings that will appeal to all segments of people. However, the Disney principle is that to do so, parts of the parks and their services will be catered or customized to the needs of only some of the family. I forgot the name of it that the Imagineers use, but the principle is that the patchwork of services geared to the various segments of people come together to form the unified and more comprehensive whole. Simply, they have offerings that appeal to all segments of guests, but not all offerings will appeal to or be available to all segments guests.
The examples people like to point out all the time as an example of this are, in fact, the thrill rides which are aimed at more adult thrill seekers. The flagship example is, of course "Alien Encounter," which was a very not family friendly ride but was developed and installed to appeal to the people who wanted something more. And "Space Mountain" is one of the rides that falls into that catagory. In fact, if you read the history of "Space Mountain" (and the ride concept it was loosely based on at DL), the whole point of putting it in was to appeal to those that Walt felt didn't have any real ride representation in the park: thrill seekers and teenagers. Walt himself said to Imagineers after "Matterhorn" was opened and turned out to be so popular that he wanted to do another ride that was a "thrilling coaster" because the guests showed him that something that wasn't a ride appropriate to everybody still had a place in his parks. I think it was one of my classes I took that even shared that the unexpected (for Walt) success of "Matterhorn" is what led him to the revision in the park's philosophy that was essentially along the lines of that adding attractions not suitable to the whole family doesn't mean that the park as a whole isn't for families, it just means the needs of the whole are met by addressing the wants of each personality.
So, even according to Disney himself, WDW and all the other parks were designed as a whole to be "family friendly," but only by including attractions and services that are not suitable for the whole family. Not everybody can enjoy or do everything, and some rides like "Space Mountain" or ToT or EE are not family friendly (and in fact very specifically exclude people from even riding). The fact you see people saying they can't/won't/hate doing X ride goes to show that all rides are not "family friendly," especially rides like "Space Mountain" as, by the words of Walt himself, they weren't designed to be.
And it has nothing to do with your beloved hamster Muffin, a long-standing and beloved member of your family, not being able to ride.