I'm glad you brought this up, as it gets bandied about a lot as if it were gospel truth. I'm not directly attacking you, but rather the idea, so I hope not to offend.
The idea raised here is that RAW are the RULES, the laws of the game, and any deviation from them is a "house rule." These are all aberations from the true rules, and thus rely on opponents' permisison.
The immediate rebuttal given is usually TMIR, the most important rule, which states that the most important rule is to insure that everybody have fun, not to follow any black letter rules.
The counter is clear: what if following RAW exactly is how you have fun? Aside from the obvious self serving nature of the position, it's a little silly, to think that the main way a player has fun is to follow the rules, not to actually have a good game.
So, you end up dead locked. If you refuse to allow shrike to infiltrate, the RAW player is having the time of his life while the other player is pretty bummed he can't use his units in the most obvious way. If you do allow Shrike to infiltrate, then the RAW player is bummed because rules are broken, while the player is having fun with his cool unit. A lot of people would state that because you can't quantify TMIR, it's not relevent for rules discussions.
Well, TMIR has no basis on RAW, but it has everything to do with how the game is actually played. It's not poor sportsmanship to want to use your units in the way the codex intends. It's not good sportsmanship to insist on playing by the rules when they're ridiculous. It might be against the technical rules, but it's not poor sport. Sportsmanship is about gentlemanly play, and that entails ceding things to your opponent.
So why should the RAW player that knows he's right cede, while the Shrike player gets a free pass? Rule of Cool. Shrike isn't broken. He's not an unstoppable unit that will easily win games. It's a cool, fun, fluffy rule that allows one unit to act in a way that the background describes. Simply put, whats more fun? Allowing a unit to act the way it was intended, or dryly enforcing a technical rule?
I contend that the argument "I have fun playing by the rules" is really code for "I have fun telling people they're wrong, and correcting them on rules." And that's fine, you can do that. But it's not sporting. Sportsmen don't just follow the RAW, or even the RAI. They follow the unwritten rules of competition, things like "keep it fair," and most importantly, "don't be a dick."