parshanut torah comment - Washing feet before coming inside: Avraham vs. Lot

When the angels came to visit Avraham, he asked them (Bereishis 18:4) to "Bathe your feet, and recline under the tree". Rashi explains:

He thought that they were Arabs, who prostrate themselves to the dust of their feet, and he was strict not to allow any idolatry into his house. But Lot, who was not strict, mentioned lodging before washing, as it is said (below 19:2): “and lodge and bathe your feet.”

However, when explaining the discrepancy in the story by Lot, Rashi (19:2) provides an alternative explanation:

Now is it customary for people to first stay overnight and afterwards to wash? Moreover, Abraham said to them first, “and wash your feet!” But so did Lot say (i.e., he reasoned), “If, when the people of Sodom come, they will see that they have already washed their feet, they will invent false accusations against me and say, ‘Two or three days have already passed since they came to your house, and you did not let us know!’” Therefore, he said, “It is better that they remain here with the dust on their feet, so that they should appear as though they had just arrived now.” Therefore he said, “Stay overnight” first and afterwards, “wash.”

From the second explanation it seems Lot might have been concerned about idolator but there was an overriding concern that he would be incriminated for having guests. Why does Rashi switch explanations which seem even to contradict each other?

[Furthermore, from Rashi by Lot it seems like the regular manner is to wash first, so why does he even question/explain Avraham's behavior? And why by Avraham does he question the discrepancy between him and Lot; a question we would not yet have until we learn what happened by Lot?]

Answer

I see no contradiction.

Both Avrohom and Lot were intrinsically against idolatry. Avrohom therefore insisted on washing the feet before coming in.

The Sodomites were most likely to exact a penalty on Lot for entertaining guests. So there was a danger in washing the guests’ feet. If their feet were still dirty it would seem like they had only now arrived.

Lot compromised on washing in the face of this danger because his attitude to idolatry was weaker than Avrohom’s. Under the same circumstances Avrohom would have insisted on the guests washing their feet.