I guess it depends on who says what, different taxonomists have different views.
The Plant List gives Agave flexispina as an accepted name, oddly enough there are no synonyms given. It also has 3 stars, many of species don't have the full star confidence which makes it sound certain.
http://www.theplantlist.org/tp...
http://www.ipni.org/ipni/idPla...
Flexible-Spined Agave (Agave flexispina)
Notice that palmbob's statement was made in 2004.
