When the polls close on 3 Nov 2020 neither JB nor DJT will be a "candidate" for the election. When the polls close, the election becomes past tense.
Though the legal battle over the outcome will rage on, POTUS will be free to sing. No longer can he be accused of "political prosecutions" to change the outcome of the election. Put your frame of reference on the morning of 4 Nov, and reflect back on the night before. Now look ahead.
Who will have an unrestricted mandate from the people to pull the plug on the swamp? Win or lose, DJT will still be President on 4 Nov, and at that time he will no longer facing an election. Assuming JB loses, he will no longer have a "candidacy" to hide behind pre-empting his inevitable prosecution for corruption, etc.