Well that’s a bit unclear, right? Imagine if states controlled by GOP governors and state congresses (so, not MA, VT, and MD) delayed their elections. That’s 223 EV. Then on election night Trump wins in MT, LA, KY, KS, NC, and say WI (the last one being the long-shot at this point). That’s 273 total, enough to claim that we have to wait until it’s safe for the delayed states to vote.
I honestly have no idea what happens in the disaster-world scenario, and find it a bit insane that the states would even consider that, but it’s not obvious what would happen.
In particular, imagine if Trump’s team has convinced him that in a November election he loses FL and AZ and maybe even TX. I could imagine a world in which those three states, all COVID hotspots with GOP governors, delay their elections. It’s just possible in that scenario that Biden doesn’t get over 270 on election night if you keep those three states from voting. IA could be another “Trump might lose so delay” state.
More likely Trump is just trolling and sowing doubt so he can claim he didn’t really lose (if he does).