Already answered those arguments in the other thread.  

EDIT:  Not really interested in rehashing the debate with koubiac
because he clearly is engaging in argumentum ad nauseam,
(also known as arguing by nagging or repetition).

If anyone besides koubiac thinks I am wrong, message me
because I always love to upgrade my knowledge.

So I won't post/debate/argue further about it here, but for those who are curious,
the arguments above fail because:

1) There is always going to be a time based targeting
or similar mechanism in a PoS coin, where it gets progressively
easier to find a block, or at the very least, give multiple chances
for nodes to form blocks (such as 1 per second).
NXT makes it easier each second to form a block, and I
believe peercoin just gives you 1 new chance per second.
However, some mechanism is necessary to prevent the blockchain from freezing
if no one produces a block.  So the attacker can
use that to his advantage to produce a long chain albeit with
greater spaces between the blocks.  Security rules can be introduced
and a discussion could be had about the best way to optimize that
without risking divergence or other attacks, but ignoring this property
and asserting the attacker simply has a very small chance to create
a chain is just ignorance about how PoS works.  

2) The rule that coins can't forge until 200 minutes doesn't help.
The attacker simply waits for his coins to mature and then can endlessly attack.
If the attack fails, it means the chain is not accepted by the
rest of the network.  Therefore, nothing changed in the attacker's UTXO,
and he can try again and again.