1: You should have asked builder whether you could release this.
2: You gave no notice or warning that you were planning this, so no one had the chance to tell you to ask builder or if it was even wanted/needed.
3: Many of your 'fixes' may have already been implemented for the next release of MM, so your patch may actually be redundant.
4: MM is still an ongoing project, so although this patch might work now, it might not on the next release.
Forum etiquette, although respected and sometimes enforced, is still not binding legality, but copying someone's work, title and injecting it into their mod thread might raise some issues.
If you ever create your work from someone elses, you MUST get their permission unless they have licensed the material in such a way that it is free from permissions.
All modifications of the Stranded II game are derivative works and are therefore subject to the license which Stranded II is released under. This means all mods carry the same license as the game or a comparable one, and being that builder hasn't applied a license, then this mod has the same 'attribution' stipulation as the game.
In layman's terms, this means you should:
1: out of respect, ask builder if you can do this with his work.
2: clearly state in some place in the 'fix' that this is a derivative work of Stranded II by DC on a modification known as Massive Mod created by Builder2-0.