The first two comments at the linked piece are worth reading, and I would tend to agree with them. Having a default position in standard contracts is typical, and the language requiring mutual consent doesn’t necessarily indicate that Amazon is, in practice, hostile to DRM. If they really are hostile to DRM there should be plenty of authors complaining about how Amazon refused to let them publish DRM-free, and this (in conjunction with the contract language) would provide better evidence of Amazon’s policy towards DRM.
