Nothing special about the Javelin, it's 20+ years old tech at this point and not very different to the Kornet. Thermal imagers have improved considerably to the point you can get good ones that don't require cooling. Think about how much phone cameras have improved in that time period. Having to wait 5 mins for the sensor to cool down is a big disadvantage, as is the bulkier CLU, and battery life.
Disassembling one for "reverse engineering" is just a complete waste of a weapon. It's not the 50s anymore, having a component in your possession doesn't mean you can make it.