How would Penang port "facilitate seamless cargo transport" across the Kra, which is about 700km away?
What 'spillover'? The Kra route is simply meant to speed up the global east-west shipping route. If a ship has to make two additional loading/unloading stops in Thailand, why would it then pull into Penang? It will mean less business for Penang if anything, as the Kra link will not make it quicker for ships to reach Penang from the east. This is all just nonsensical hype to generate funding.
They should look to the Dawei debacle, which was a waste of billions of dollars because nobody dared ask common-sense questions.
The Dawei 'land bridge' was meant to provide a boost for Laem Chabang at the other end. They've forgotten about all that?