Because he's said so himself that all efforts go to Crediar. It's slight changes in patches.c AFAIK that are merged from older versions of DM. Not revolutionary, but fixes are always welcome and very much appreciated.
It doesn't matter who wrote the original code, Crediar broke games that were working before and never cared to get them fixed again, wither he neglected them in purpose or they were broken in favor to fix other stuff is beyond me but this doesn't change the fact he didn't react on fixing them even though according to what you said is a very simple fix, which btw not all of us can do that stuff, I know I can't and I'm sure most DM(L) users can't compile and swap patches.
Crediar maybe a great programmer but his manners and personality aren't so great imho, I respect his work nonetheless, but he rarely responds to any comments, he never takes bug reports seriously and just assumes you're doing something wrong without even trying the reported games, I tried to report many times games like Looney Tunes Back in Action, Namco Museum, and Pac-Man World Rally for audio streaming issues, Virtua Striker 3 for not working while compressed (not sure if it's been fixed, last I checked was with DML 1.5 then stuck with the uncompressed version) but he never took them seriously or let anyone add to the compatibility list.
People have reported that SD compatibility broke with DML 1.0 while it worked fine in older versions, he totally neglected that and gave them the middle finger, they reported USB compatibility being broken, he didn't care, they reported sleep mode issues, took him a long time to fix and even then he didn't provide a proper fix, it only fixed SOME hard drives, then came airline38 and provided the proper fix for sleep mode, he tolerated me and asked me for testing one version after the other until it worked.
Crediar then made a mod of DML to run TriForce games, he totally kept it a secret and didn't share it with anyone, which is totally his right I'm not saying otherwise, then when it was leaked he punished those who did nothing wrong and released an early build and said (THAT'S ALL YOU'RE GETTING, BITCHES) a short time after he released a couple of videos showing progress of Quadforce running more games and having save feature and USB support, saying he's never to release them in public, what's the point of showing them off if you're not planning on sharing them? That was a d*ck move if you ask me!
airline38 cares for bug reports, he tries to help and support the project the way he can, Crediar doesn't, this makes me respect airline38's work more and respect him as a guy in general, if I'm to donate for one of them I'd choose airline38 because while Crediar may have wrote the original codes it doesn't help if he broke them later on or didn't care to share fixes!
And what the helk r u talkin' about? Crediar and team haven't abandoned this project. They're even working on enhancing the compatibility of NMM.
Well last I heard they said he backed his Wii again and said he's moved to a different project, I really hope they'd enhance NMM compatibility because I'm thinking to switch on using it with games with bigger save files that I don't intend to keep after I beat the game, well that and it maybe a good start for DM(U)!