Really, the creation of a secondary market only increases the odds of a speculative panic if we begin to sell off.
If a lot of the volume is done in the secondary market (ETF) rather than the primary market (Trades in the underlying), this may cause a problem later.
The secondary market is just an idea. People can buy and sell shares of the ETF without dealing with the underlying. It's much more liquid. All you do is click a button and it instantly happens.
But that's not how it works for the ETF that has to deal in the primary market.
They need to go into the real market and find a real buyer for all the dumping of the virtual BTC.
Which means, if there's a panic sell off - there's going to be a flood of sellers in the secondary market (And they will sell, because they don't care about Bitcoin and the idea - they're betting on the price and will be fickle), and then this translates to the ETF having to dump in block orders onto the primary market.
Creating an imbalance of support and demand in the primary market, which means there's a sell off in the primary market.
This then creates more selling in both the primary and secondary markets - and that's how capitulations happen.