In light of this quarantine, If someone is spending shabbat at non-observant relatives and the house is not kosher. If the person runs out of paper plates, would he be able to eat from a glass plate that had had non-kosher food on it at one point in the past as long as it was thoroughly washed so there are no visible stains (which is permissible unless I am mistaken according to Sephardic authorities).

Note that this assumes that the person was unable to run to the store to buy new paper plates.