Considering that a native port was the minimum expectation by 100% of linux users who paid for this

Of those who paid for it, yes. Not everyone waiting for the Linux version backed the kickstarter or has been following development since then, though.

"...Oh, we are taking longer because we are building a car, not a motorcycle."

IMO a better analogy would be 'it turns out we we couldn't make some of the car parts with the tools we had available, so we had to make the tools ourselves, since we didn't just want to jerry-rig an existing car and call it custom'.

they should have known from the beginning

Yes, as Lar said in his post.

and patting yourself (Larian) on the back

That really was not the intent of the post.