If indeed these are true positives it is most likely they had /someone/or fomite/ infect him purposely.

They infected someone they knew would be close to him in the upcoming days, easily done because that person doesn't have everyone in their premise tested everyday. By the time that person tested positive he was already unknowingly infected.

They deployed assets to intentionally infect Trump and everyone around him.

He received treatment and is doing well after showing mild symptoms.

This was done at this moment in time for obvious reasons.

Btw, when is the next debate?

That's an end to the airport rallies this year.