It's no more far-fetched than they spending astronomical amount of money to attack a PoS system (and without guaranteed success, like attacking a PoW).
Forging a POS coin allows for easier wealth accumulation than with PoW as existing ASIC manufactures have to take risks with investments and reinvest their gains in new equipment and miners are forced to spend a majority of their profits on new equipment and electricity. POS and DPOS is essentially a framework where large stakeholders collect usury off the network and even if you have a very fair initial distribution model you will have unequal wealth accumulation over time because most of the profits are compounded instead of reinvested at a loss.
With PoW you can easily know in realtime if there is a mounting risk from a mining pool, ASIC manufacturer, or miner. With POS or DPOS one individual can slowly buy up a 51% stake under many Pseudonames with no one noticing. Governments cannot build a large mining factory without leaks as evidenced by the high amount of top secret intelligence constantly leaking. Some people mistakenly assume that Snowden was the first leaker of the NSA programs when people in the IT field where knowledgeable of many of these programs shortly after 9/11 and all Snowden revealed was further details. The bitcoin community would find out about any special program and react just like we constantly do when a mining pool gets near 50%.