I could be wrong but my perception is that Atom is losing market share to VSCode all on its own– new devs are much more likely to adopt vscode & no growth ~= decline for an editor. Couple that with the fact that no one pays for Atom...
IMO They don't need to "kill" atom, they just need to wait a couple years, at which point it will just Yet Another Editor down the list with TextWrangler et al., if the next Atom doesn't come along and hasten its decline even further.