What you've said is correct i think. Made an RTI for this and got some shocking results...

KCVL has free slots (pit line number 4). But it will create impact in occupation & loading of pitlines at KCVL due to which no new or special trains can be operated from there.

Sadly...
more...

Alappuzha didn't have any IOH SHED, COACHING SHED, WAGON DEPOT SHED & C&W OFFICERS. It just have a pitline workline facility. (Even Shoranur with a pitline capacity of 10 ICF coaches owns all the above mentioned facilities and maintaining only a handful of 2 to 3 train rakes of Nilambur Road Passenger Trains Rakes)

But SR could have constructed these facilities rather to destroy this pitline why because constructing a pitline now a days is not that easy task and Allappey has it by luck.

One small impact in this is only one train got extended to TVC once again. That proposal pic is also attached for readers reference.

INSTEAD SOUTHERN RAILWAY CAN UTILIZE THIS PITLINE BY MAKING THE PRIMARY MAINTENANCE FOR ALAPPUZHA CHENNAI CENTRAL EXPRESS & ITS RSA CHENNAI CENTRAL TRIVANDRUM EXPRESS HERE SO THAT IT MAY DECONGEST THE BASIN BRIDGE YARD SOMEHOW SO THAT NEW TRAINS CAN BE OPERATED IN THAT SPECIFIC SLOT FROM CHENNAI.

But for this, the Chennai Allappey express should be speeded up from Palakkad Junction to ALLP as this trains' top speed in this entire kerala route is only 60 KMPH whereas from CBE to MAS it has 120 KMPH. So that it can reach ALLP by before 8 AM so that it can do Maintenance works there itself with 6 hours of Scheduled slot.

Alappuzha executive express can also be considered for this...