They are suggesting that the "Last Supper" was just a regular meal prior to Passover.

Passover – the Feast of Redemption – is a day of reckoning! Do you know what purpose it serves? Do you know it is one of the commanded feasts? Do you know it is an eternal feast that we will celebrate in the kingdom?

Passover and spring are upon us. If you are like me, then you are anticipating the newness of life as the warmer weather brings a renewal of life to the trees, plants, and green grass. It is also the time of year to renewal of the story of Redemption. It is no wonder that God commanded us to keep the Passover in the spring, and that He used the Passover to give us the resurrection of the Messiah.