[@Steel Legion] For the most part it's good, except the last bit at the end where he's reincarnated multiple times as different creatures. Being reincarnated as an Orc is the first time any of the player characters' souls have been brought into this new world, they didn't start off as lower life forms or anything. Also, if he started his company in the 70s, he'd have to be older than 55. 55 years ago from today would've been in 1968, so he wouldn't even have graduated high school until the 80s. 

Other than that I like him, and I'll have your Isekai skill choices up this evening!

[@Lucius Cypher] If Gren figured out a way to eat the coilbone, he'd have enough to figure out the last ability. However, attempting to just chew it would be like trying to eat those big cartilage bits you sometimes get in a rack of ribs/fried chicken, and each segment would be too big to swallow whole at his current size.