Clarify the Spot of Enforcement

[golfdesigner]

Good morning all,
Watched this one last night with a Varsity crew.
NFHS Rules.
LOS is A 30-yd line A 2nd down 7 to go;
A10 takes snap and rolls out;
A79 is flagged for hold behind LOS, about 4-yds behind LOS during A10's roll out;
A10 throws legal forward pass to A88 (complete);
A88 runs for about 10-yds after catching pass to B 30-yd line;

Crew marched off 10-yd penalty from PS and replayed the down 2nd and 17-yds to go.

We discussed basic spot, since the roll out preceeded the pass, the run was part of a loose ball play, the basic spot would be the previous spot.

The foul would not be assessed from the spot of the foul to make it 2nd and 21-yds to go.

Anybody want to weigh in on this one?