That's just the brake booster line. It defeats the purpose of what figure 1-4 exists for (to find a line that doesn't run seafoam through your rotors).
The only line that does is the one under your snout in the lower intake. It's the same one that runs to the FPR, boost solenoid, and map sensor. I guess you could disconnect the map sensor temporarily for the seafoaming, but that's a small vacuum line to attempt it through.
I've still got a can of seafoam just sitting here. I guess I should use it, but I don't feel like buying plugs and installing new ones yet.