Most MM tarantula's never survive their post-ultimate molt, and even more don't even get there to find out. They're not built to molt with the tibial hooks and if they're lucky enough to live long enough to try, this is where they get stuck and fail. There are some very rare cases where MMs have survived their post-ultimate but it's so rare that you can pretty much bet the farm in the other direction.

There have been recorded cases where a MM has lived nearly 5 years after their ultimate molt. Most will pass away peacefully within 6-12 months. Given that the one you have is only 2 years old, there is a higher risk that he may try to molt again despite reaching maturity already. The best thing you could do for him right now is find him a date! Any breeders or avid hobbyists locally that have a MF of their own and want to pair them up, or you can always try posting on a few of the invert/tarantula forums and sell him to a breeder. A lot of people will do 50/50's where you ship the MM to them, they pair it with their MF, and when the babies arrive send back half the brood. This is only beneficial to you though if you'd like to have your hands on 100-250 tiny G rosea's.

If we discover you have a female yourself, there's a date right there! Will's right though, the shots are great but sadly the area we need to see (the forward book lungs, where we see mostly the rear ones in those pictures) is somewhat obscured. What you're looking for there is an enlarged group of setae generally accompanied by a darker triangular or half moon patch. The way to be 100% though is to save your next molt and look for the presence of spermathecae. between the forward book lungs.