No, PoS is not legit. All closed entropy systems are technically permissioned ledgers that are not decentralized, which will likely give them enormous legal problems in the future.
All stock markets are, in your words "permissioned extortion schemes" as well, will it give them enormous legal problems?
The stock market consists of people who aren't anonymous coming to the table and saying, "buy this shit from me", with some expectation of returns. It's a market subsidized by the government where they use coercive powers to "presumably" stop people from running blatant scams. If you issue things in a centralized fashion the way they do, they lump you into the same legal framework.
There are a few coins like peercoin and blackcoin that are entirely mined that might escape this legal framework, but they're still closed entropy systems that aren't decentralized currencies. Not to mention having horrible fault/state recovery and millions of other problems making them inferior to PoW
1st. Your Entropy & Permissioned arguments are
Child like Nonsense as Even the Multiverse is Technically a Closed System and every PoW system requires permission to enter.
2nd. Only People in the US acting as Intermediary (taking in money as an investment and paying out interest directly)
basically acting like a fund manager would have anything to worry about,
The IPOs where only the coin was sold to the end user and that was it, will not fall under the US SEC jurisdiction.
IE: (Most IPO Transactions handled by exchanges are the same as if you created a painting and sold your art work, as such will not fall under the US SEC jurisdiction.)
3rd. PoW is an Economic Failure due to the constantly increasing input costs, and only BTC Shrills blind their selves to that revelation.
A. Becoming a BTC miner is Blocked due to the Financial costs making it a closed system to the majority of the World's Populace.
B. ASICS are Useless after 1 year due to difficulty increases. ASICS ARMS RACE where only the Mega RICH can win.
C. China already controls over 60% of BTC mining pools
(51% attack whenever they feel like it)