Unlike the other one you sent me, at least this is a reasonable question that needs an answer. The reason this could be at least somewhat confusing is that John tells us (John 19:38-42) that when Jesus’ body was laid in the tomb of Joseph of Arimathea, Nicodemus included about 35 kilograms of myrrh and aloes. Why, then, if the women saw this (we know they saw this from the account of Matthew and Luke, for example Luke 23:55-56), did they come back on Sunday to add spices and perfumes?
My answer, is that I do not exactly know why they did it, but I know they did! How? Because Matthew and Luke, who are consistently reliable witnesses tell us that they did. Why would they do this? I already said I am not sure, but if we are going to claim that there is a contradiction, then the burden of proof is on the one who claims a contradiction. Why not? Why shouldn’t they bring these spices and perfume to honor Jesus. When there is a funeral, people bring flowers. Do they ask if there are already flowers? No, they do not. Do they ask if there are enough flowers yet? No they do not. Why do they bring flowers? To supply a need of the dead person? No. They do it to honor the dead person. When we honor dead loved ones, we do not ask if they are already honored enough. Perhaps the women simply did this to honor Jesus, who they loved. The fact that there were already myrrh and aloes did not lessen their desire to honor Jesus by bringing spices and perfume. This certainly is not a contradiction. Another possibility (I am not sure, as I am not an expert in ancient Jewish burial practices) is that the spices and perfume they brought was in addition to the myrrh and aloes. In other words, there may have been a tradition to include not just myrrh and aloes, but also other spices and perfumes to lessen the extent of the smell of death.
This Rabbi Singer is trying to prove that one of the gospel writers is simply wrong. He will need a lot more than this to establish that one of the authors made a mistake. The people who were actually there, such as Matthew and John, are more likely to know, not only the customs at that time, but also what actually happened than Singer. This Rabbi should stop publishing these misleading claims in my opinion.