It's not really a changed definition. I'm just assuming he's going to fail to win re-election in 2028.

> An elected officeholder or group continuing in office during the period between failure to win an election and the inauguration of a successor.

Many senators aren't going to be up for election until 2030. Their allegiance to Trump due to his influence only lasts as long as he can threaten their re-election 2 years after he's an ex-president (and let's face it, he's quite old...). As I've said, we've already seen his influence fade. Just a bit, but this kind of thing goes fast once it does.