Hmn. Well, first and foremost, let me offer a bit of information.
No diseases work in Felarya.
Period.
It's been established that bacteria, viruses, and other diseases are not capable of operating in Felarya due to the soil/water/atmosphere, which essentially supercharges the immune system to an absurd level. Therefore, a good chunk of this character is already null and void. Going to Felarya, if anything, would impede his research even further.
There is also the fact that he 'no longer fears death'. He is not going to last long in Felarya. There are plenty of plants, animals, and other hazards more than willing to have a go at him, and a fair chunk of them won't swallow him whole only to vomit him up again. Being inedible is no help if you're torn apart and scattered over a few dozen yards of jungle. Not to mention all the snakes, spiders, insects, and other small animals that are venomous enough to kill with one nip.
However, the base concept of a scientist in Felarya for research isn't a bad one, you simply picked the wrong sub-category for it. A geneticist or biologist could be a better option, if you like. I would recommend taking the base idea (scientist in Felarya for research) and start over with that.
Do note, read the Felarya Wiki before trying to make a character/race/animal/anything. It definitely will help you.