The issue is quite simple and breaks down like this:
1 - 'The Wall' is perfectly legal. There is a large white line that is considered out of bounds. Players and coaches can not be on it during a play. The players were not on it. The gunner is allowed to go out of bounds, i.e. the big white line, and even beyond, but must make every effort to get back quickly. This assumes they are directed out by the coverage. If this wall is 'bad', then the rule needs to change and/or that thick white line needs to be thicker.
2 - The trip was wrong. No one on the sidelines is allowed to intentionally interfere with the play. If the player is allowed to be out of bounds during a play, then the fact that the player was that far out is irrelevant. He is live and is not to be interfered with INTENTIONALLY. Again, modify the out of bounds rule if the league does not want to police the intentions of any contact made by sideline personnel.
**WARNING - SLIGHTLY OFF-TOPIC RANT**
Now, let's pretend that this wall was in fact illegal and widely practiced. IF that's the case, then the crime is far worse than videotaping signals. This is directly influencing the play of the current game. It is not some vague notion that some play in some future game, maybe even years down the road, might be influenced by recognizing a signal that was once videotaped. Even in that case, player execution is key. You can have the right play called, know what's coming and still fail. Having a reasonable idea of what the play might be only improves your chances on that single play. It doesn't guarantee anything. Heck what if your analysis was wrong? Directly influencing the play with personnel other than the 11 players you have assigned to the field is far worse than using stale information to influence strategy on a couple plays in the future. But again, unless tripping people is regular practice (lol of course not), there was nothing done wrong here outside of Alosi's knee-jerk or jerk knee or whatever you want to call it.