Actually with the font exploits an interpreter would be quite a bit safer. Many of the font exploit chains work by creating line vectors that result in an infinity or NaN throwing a floating point error (with the SeH handler already being overwritten). When running this by JIT... all of this is occurring on the physical CPU. If the floating point calculations were occurring inside an interpreter then the SEH chain can be protected by SEHOP/SAFESEH and the interpreter could implement bounds checks and while retaining the NX bit on everything executing.