I really hope it's not a prequel. It would make everything that happens in Hiveswap not matter because we already know none of these characters appear in Homestuck

You really can’t hope for it to not be a prequel though, it is. However we don’t know that it doesn’t matter. First of all, the Cherub Portal could let them escape the fate of their planets some way. Second, given Scratch is involved, it’s likely all of this explains something we don’t know about from Homestuck just yet. Then, if Joey gets back to Earth and Jude survives whatever happens in Hauntswitch, they can still play SBURB when it comes out. Also Xefros and Dammek were going to be sent off-planet and exploited by the Alternian Empire in like, a few sweeps, we know their revolutionary efforts are going to do nothing, but they may pave the way for something later on. If anything, Hiveswap giving these characters attention is giving them a way to do something and perhaps escape the fate of their planets, rather than dooming them to it.