Cote CO does not manipulate the brain, it very gently massages the bones in the skull to release trapped tension and nerves - it would have to be quite forceful to affect the brain in anyway and it isn't - it is extremely gentle. If a babies brain was damaged that easily every knock and bump would be investigated in A&E
Do you think birth causes brain damage because the movement and pressures the skull are put under even during the most text book birth are a thousand times more than during CO. Do you think all babies should be born via c-section to prevent damage to babies maleable skulls?
You compare the results to having holes drilled into skulls - which again is odd as those people became more docile due to brain damage which changed their behaviour - CO doesn't change behaviour, it relieves physical symptoms.
While there is no peer reviewed evidence to say that it works, there is enough anecdotal evidence to suggest that it works - I have yet to see any scientific or anecdotal evidence to suggest that it causes any form of brain damage.
Based on the fact that there is no evidence to suggest it causes damage, I'd much rather use CO which cured DD1's reflux than pump a baby full of biological glue which effectively plugs the gastric tract preventing the body from carrying out a natural function, thereby masking the problem rather than curing it.
You say you think it is dangerous, yet the only link you provide is one to say there is no evidence of it working not that it causes damage - making your assumptions as lacking in evidence as those people who believe that it works.
If it's not for you - fine, no one is forcing you to take your children to a CO, but there is really no need to berate people who have used it and found it helpful.