That's one possible interpretation. I'd be inclined to rule that a failed SV means the character is entangled for the duration of the spell, so treated as prone for the duration. In other words: it's a deadly spell, especially as it's only 1st level.
"It is all very well to point out that the man lacks facility; as he asserts, sheer force can overpower sophistication."
Jack Vance, Rhialto the Marvellous