According to the following extracts I think you should be OK casting
with it.

The new twist n lok butt enables the length of the butt to be extended
for casting and shortened for playing fish.

Twist and lock butt Feature
The new 'twist n lok' butt enables the length of the butt to be
extended for casting, and shortened for playing fish, turning a casting
rod into a fishing rod in seconds. Long handles have always been a
problem, especially on small boats where room is minimal. The Abu
Suveran and Conolon Pro Uptide rods solve the problem.

Whilst this refers specifically to Uptide boat rods I believe the
principle is the same for all rods with a reducer, which I believe is
more intended to reduce the length of the rod when playing fish rather
than reduce the diameter of the reel seat.