Another onsides kick question

[rdfox]

Had a strange onsides kick last week. I believe it's legal under NF, but would like other's opinions.

Kicker places the ball on the ground on the 40, long axis parallel to the 40. All members of K are gathered the kicker.

Kicker softly kicks the ball, which essentially started rolling (he has obviously practised this kick many times). The members of K all start moving forward surrounding the ball. Obviously, no one touches the ball. They block one or two members of R out of the way...kind of making a path for the ball to roll the required 10 yards.

On the 11th yard, the kicker falls on the ball. K's ball 1st and 10.

R's coach went nuts, but I couldn't come with any reason why it would be illegal.