Claim that vaccines aren't 100%: http://www.mayoclinic.org/diseases-conditions/measles/expert-answers/getting-measles-after-vaccination/faq-20125397

More than 93 percent of people who receive the first dose of MMR develop immunity to measles. After the second dose, 97 percent of people are protected.

So my numbers were off, there you go.

Claim that measles doesn't mutate and isn't at risk: I would think this is self-evident as it never has throughout generations of vaccine usage. But sure, here's a white paper on the genetic stability of measles virus: http://jvi.asm.org/content/73/1/51.full

The mutation rates we estimated for measles virus are comparable to recent in vitro estimates for both poliovirus and vesicular stomatitis virus. In the field, however, measles virus shows marked genetic stability. We briefly discuss the evolutionary implications of these results.

Myriad factors could contribute to this stability, including the lack of recombination in morbilliviruses, strict constraints on insertions and deletions, the limited host range of measles virus, and functional constraints due to measles virus’s protein receptor. In the context of measles virus elimination efforts, evidence for a high mutation rate suggests that the possibility of strains that may escape neutralization by vaccine must be considered, although to date there is no evidence of such vaccine-escape mutants.

Claims that the primary risk to children from unvaccinated kids is introduction the disease they are already vaccinated against: http://www.sciencedaily.com/releases/2012/08/120822181234.htm

This source does not corroborate my claim that it's the PRIMARY risk, but it does provide evidence that disease outbreaks are due to unvaccinated children.

Honestly, I believe I could round-a-bout prove this point by showing that A) unvaccinated kids lead to decreased herd immunity, B) herd immunity is the biggest risk factor for children, and C) that vaccines aren't 100% effective individually meaning that herd immunity is required for individual protection. But I can't find a source that empirically analyzes individual risk rates between vaccinated and unvaccinated kids. I stand by the assertion that the never-before-occurred mutation past vaccine efficacy won't happen, and that herd immunity breakdown (and the subsequent risk that individuals face in light of a 97%, not 100%, effective rate) is the #1 factor why being near unvaccinated people is dangerous.