Pointlessly bumping is against the rules, bumping with a reason is fine*
*as a great video once said "It is always better to post in an existing thread than start a new one".
Homebrew is not always fast moving either, the wii u is in a bit of a state of flux, as is the vita and the 3ds has calmed a bit (what you knew 3 months is probably still OK at this point, and more broadly install custom firmware or sky3ds is still what goes) but is not perhaps as stable as some other consoles. ROM hacking is almost never fast moving, I know some games have updates but even they tend not to radically redo things. Threads in off topic generally are fine (new developments in cases/news stories, DVD release of films/TV shows hit, hearing someone else's favourite whatever is fine by me).
Short version. There are many good reasons to post in old threads, people needlessly bumping old threads is not a major problem on the forums and the report button and moderators are there for a reason.