Why is it necessary to clear the Keilim from the house before the Kohen arrives?
Rashi #1: To prevent them from becoming Tamei, because until the Kohen arrives and declares the house Tamei, they are Tahor. 1
Rashi #2: Refer to 14:34:3:1*.
Seforno: It is to allow the owner time to do Teshuvah and for him and the Kohen to Daven to Hashem for mercy. 2
Bearing in mind the immense value of a house as compared to that of a garment. The Seforno then cites a Midrash that the sequence of events regarding a stricken house hints at the destruction of the first Beis-ha'Mikdash, its rectification via the building of the second Beis-ha'Mikdash, the destruction of the second Beis-ha'Mikdash and its purification via the building of the third Beis-ha'Mikdash - may it come about speedily in our days.
Why is his necessary? Why can the owner not simply Tovel the Keilim after they become Tamei?