FR 8-2-1-a
SECTION 2. Touchdown
How Scored
ARTICLE 1. A touchdown shall be scored when:
a. A ball carrier advancing from the field of play has possession of
a live ball when it penetrates the plane of the opponent’s goal line
(Exception: Rule 4-2-4-e) (A.R. 2-23-1-I and A.R. 8-2-1-I-IV).
FR 4-2-4-e
e. When a ball carrier dives or jumps toward the sideline and is airborne as
he crosses the sideline, forward progress is determined by the position
of the ball as it crosses the sideline (A.R. 8-2-1-III and IV).
FI (A.R.) 8-2-1-III
III. Ball carrier A1, advancing in the field of play, becomes airborne at
the two-yard line. His first contact with the ground is out of bounds
three yards beyond the goal line. The ball, in possession of the ball
carrier, passed over the pylon. RULING: Touchdown (Rule 4-2-
4-e). No mention of ball crossing sideline while ball carrier is airborne
FI (A.R.) 8-2-1-IV
IV. The ball, in possession of airborne ball carrier A21, crosses the
sideline above the one-yard line, penetrates the plane of the goal line
extended and is then declared dead out of bounds in possession of
A21. RULING: Ball is declared out of bounds at the one-yard line
(Rules 2-11-1 and 4-2-4-e).
Goal Lines
ARTICLE 2. The goal line at each end of the field of play runs between the
sidelines and is part of the vertical plane that separates the end zone from
the field of play. This plane extends beyond the sidelines (Exception: Rule 4-2-4-e).
The two goal lines are 100 yards apart. The entire goal line is in the
end zone. A team’s goal line is that which it is defending (A.R. 2-11-2-I).
Since the goal line runs between the side lines, in the original post where it says that the ball touches the pylon on the outside edge it would have to have first penetrated the plane of the goal line extended as referenced in FI (A.R.) 8-2-1-IV
FR 1-2-6
Pylons
ARTICLE 6. Soft, flexible four-sided pylons 4 inches by 4 inches with an
overall height of 18 inches, which may include a 2-inch space between
the bottom of the pylon and the ground, are required. They shall be red or
orange in color and placed at the inside corners of the eight intersections
of the sidelines with the goal lines and end lines. The pylons marking the
intersections of the end lines and inbounds lines extended shall be placed
three feet off the end lines.
Since the pylons mark the intersections of the goal line and side line and also the end line and sideline, and the goal lines run between the side lines it sounds to me like the pylons are out of bounds.
And just because I know someone is going to bring this up:
FR 2-31-3
End Zones
ARTICLE 3. The end zone at each end of the field is the rectangle defined
by the goal line, sidelines and end line. The goal line and goal line pylons
are in the end zone, and a team’s end zone is the one it is defending
(A.R. 8-5-1-X and A.R. 8-6-1-I).
So you can take this one rule that says the pylons are in the end zone and build a flimsy case for why you would award a touchdown, or you can take the two rules and two A.R.'s which all specifically list an exception referencing FR 4-2-4-e plus the one other rule that I have listed and build a solid case for ruling the ball dead at the point at which it crossed the sideline.
You decide; but choose wisely.