I believe it shouldn't be an issue. However, it is best to also add a check before removing the layer in case the active cell is in edit mode. If it is in edit mode the moment the layer is removed a null reference exception is thrown. Maybe this situation will not be possible in your scenario, but it's better to be on the safe side.
Also, as the order of the UI layers is important, we should add the layer in its previous position, which is before the resize decoration layer. With these two in mind, the code should look similar to this:
RadWorksheetEditor editor =
(editor.Selection.ActiveCellMode != ActiveCellMode.Edit)
CellInputLayer = editor.ActivePresenter.UILayers.GetByName(WorksheetPredefinedUILayers.CellInput);
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