That is not idolatry. That is called "Veneration." Look it up. Respect for something believed to have been left behind by Jesus Christ himself as a testimony of what happened. You use the term "idolatry" as a pejorative. if you had possession of the Robe that Jesus wore while preaching and spreading God's word, would you spit on it or venerate it?
He told Thomas to put his fingers into the wounds in his side. . . so that he would believe. Why not accept that perhaps he left behind a testament to his death and resurrection?
Someday when you have time, delve into the etymology of “venerate.” The Latin root means to worship or adore. I’m sure you can find long documents explaining why venerating and worshipping are different acts. Regardless, Rome has a long history of treating created things as if they were due the reverence of the Creator.
As for such a robe, I would likely burn it lest it be a stumbling block for sinners prone to the worship of material things instead of the Lord. The Lord is to be worshipped in spirit and truth.
By the way, Jesus also told Thomas: “Blessed are those who have not seen and yet have believed.” Christians are to walk by faith, not by sight! (2 Cor 5:7)