This effectively says, "Ms-RL defines the rights granted to you. Any rights not granted to you are not granted to you." As a tautology, this assertion has no practical effect but is also practically harmless (except to cause some confusion).
This answer nicely covers the history of the related phrase "All rights reserved." In brief, "All rights reserved" was once necessary (many decades ago) to establish copyright, regardless of how you chose to license a work after you established copyright. This phrase is no longer necessary, but it was kept by BSD (and perhaps other projects) in an abundance of caution, which has led to the phrase's continued needless reuse today.
This variant, "All other rights reserved," is correct but legally obvious: by definition, you reserve any rights that you do not grant.