When you use an ability that requires you to be in caster form while shapeshifted, the client checks a console variable called "autounshift". If that variable is 1 (true) then it will automatically cancel your form and then cast the ability, if it is 0 (false) it will not unshift you and the ability cast will silently fail.
Since Predatory Swiftness (or Nature's Swiftness) allows the ability to be cast in form, the cast line only succeeds when the player has either of those buffs up.
A simpler form would be to simply set the variable to 0 using the console slash command, then cast the spell, then set it back to 1. The macro I provided is a tad more complicated and instead only sets the variable to 0 if you're in combat, that way you can freely pre-cast a Healing Touch outside of combat without manually having to shift out.