Why was Vallarpadam port constructed despite Vizhinjam being a better choice ?

Vizhinjam has three advantages over Vallarpadam

1). No dredging needed - Vizhinjam has a depth of more than 20m, so no dredging needed. Whereas Vallarpadam requires constant dredging. Dredging costs money and is a recurring expense.

2). > 20m depth means Vizhinjam can accommodate mother ships and can act as a Transshipment port, mind you, this is India's only trans-shipment port. Whereas Vallarapad has no strategic importance. One can argue that since Kochi is more industrialized than TVM, so a port at Kochi makes much more sense.

3). Proximity to International sea route - Vizhinjam is just 18 KM or 10 Nautical miles from International sea route. Whereas Vallarpadam is 74 kilometers (40 nautical miles). This means ships dont have to deviate much from their designated route to drop off shipments at Vizhinjam, whereas for Vallarpadam, they have to take a detour.

All these advantages for Vizhinjam, still the Government went ahead and constructed a port at Vallarpadam. It seems like some group lobbied hard for a port at Vallarpadam. My initial suspect is Kerala congress, since they are quite popular in Central Kerala, they will want a port close to their home turf. One conspiracy theory i read online is that DP World (main investor in Vallarpadam) sponsored Vallarpadam because they knew that Vizhinjam will be a direct threat to Dubai port since both are Transhipment ports. The logic here is that if Kerala has a port in Kochi, we will not have the money or the political will to construct another one at TVM.

From a layman's standpoint, constructing a port at Vaizhinjam is a no brainer. A news article about problems faced by Vallarpadam

I was a school kid during the Vallarpadam construction days and was not into politics or kept myself abreast with current affairs. If you are aware of the background of Vallarpadam port being approved and constructed, please comment on this post.