Yes and no. The (delightfully named) bitdiddle may have a point.
Although the CME futures will be cash settled so Bitcoin will not be directly involved, it's not clear what would happen if there was evidence of price manipulation.
For example, if there is an anomalous spike on a stock exchange around the time of the futures mark, this is always investigated.
If a similar thing occurred on, say, GDAX (which will be included in the benchmark), it's not clear what that would trigger. It's possible that the answer is nothing (there are futures on Libor after all) but it doesn't require much tinfoil to see this as a possible point of attack.
My point is that, just because the futures are not directly linked to Bitcoin, they can still have a direct effect.
And I'm not suggesting that they're listing futures in order to attack Bitcoin. I have no reason to believe that.
However, it is notoriously hard to prove general price manipulation. It is much easier, and more common, to prove specific price manipulation. In practice this usually means an extraordinary anomaly e.g. a flash crash or a targeted anomaly. The latter is almost always due to a specific event such as a rate setting or a close price.
Although the CME futures will be cash settled so Bitcoin will not be directly involved, it's not clear what would happen if there was evidence of price manipulation.
For example, if there is an anomalous spike on a stock exchange around the time of the futures mark, this is always investigated.
If a similar thing occurred on, say, GDAX (which will be included in the benchmark), it's not clear what that would trigger. It's possible that the answer is nothing (there are futures on Libor after all) but it doesn't require much tinfoil to see this as a possible point of attack.