inherently less secure and encourages mining centralization. best case expect a MM of 50% that of Bitcoin. that is insecure. see https://www.reddit.com/r/Bitcoin/comments/2k01du/peter_todd_on_twitter_the_sidechains_paper_is/clgpjpx
you just pulled that 50% number out your ass heh
so peter's argument is dependent on a country outlawing the mining of a sidechain... that should work out well 
honest people will realize that if we return to your favorite pet, the anonymous sidechain, then on the contrary I find it very likely that most of the miners adopt it for MM considering it is trivial and introduces a new revenue stream for them.
ohhh but wait, maybe the country will outlaw it..
wrong. you just ignored Adrian's model of declining BTC fees paid to Bitcoin miners, a result of ppl moving to scBTC b/c of the risk free put and innovation. all the tx fees will migrate to the SC leaving Bitcoin miners no choice but to defect.
WRONG. Refer to mistake 2, no one wants to move all of their BTC to scBTC because they are essentially UTILITY chains. They do not, on their own, offer more value than BTC's chain. Adrian's only possible scenario where the mining incentives are more important on a scBTC than on BTC is effectively through an altcoin. Even then, miners would continue mining the BTC blockchain until NO value can be pulled out of it (read: dead). You are therefore arguing an altcoin will take BTC over, a valient concern, but one that Sidechains do not introduce nor greatly enable
the correct way to look at this is you are breaking the link btwn the MC and its BTC by moving highly secure BTC to relatively insecure scBTC. the equilibrium price of BTC will go DOWN.
FACT : it is trivial for miners to merge mine just about any chain and they will if there is ANY value in it.
The scenario you refuse to acknowledge is this one :
Adam, Gmax and the crew announce that after months of testing, they are introducing the anonymous sidechain. A sidechain that, I quote, as been
extremely well tested and coded to the same rigor as bitcoin itself.
While the developer team was busy cooking up this good stuff, our friend Austin Hill, having previously developed significant business relationships with major miners, reaches out to them and is able to obtain their support for the mining of the sidechain. On the day of the launch, he annonces that he was able to secure 75% of the mining power in order to bootstrap the security for the sidechain.
Eventually, and most likely not too long after the launch, the other miners realizing they are missing out on a potentially rewarding revenue stream add their support to the sidechain, essentially capturing MOST of the hashing power of the network to merge mine anonymous sidechain.
Considering the apparent serious implementation and backing behind the sidechain, the market starts using it and finds considerable value in it. price of BTC goes UP