shlichus to deliver bikurim

The gemara B"B (81) quotes R’ Yosi bar Chanina who derives from the juxtaposition of "v’lakachta...v’haveisa" that the lekicha and hava’ah of bikurim must be done by the same person – i.e. if the owner harvests the fruit but it is delivered by a shliach, or a shliach does the harvesting and the owner delivers it, the parsha of bikurim cannot be read. Tosfos and the Rashbam disagree as to whether lekicha refers to the harvesting of the fruit (Rashbam) or to taking the fruit from the house and setting out on the trip (Tos.)

The Minchas Chinuch assumes that if the shliach or owner did the lekicha and started on the trip, even if someone else took over in the middle, as long as the same person who started the journey completes it, the parsha of bikurim may be read. Completion of the trip is defined as arriving at the azarah.

Rashbam writes that even if a shliach delivers the bikurim, the owner personally must recite the parsha of viduy bikurim. The shliach cannot read on behalf of the owner because he cannot refer to “adamah asher nasata li”, the land given to him, as he is not the owner. The owner, however, can still say “hinei hayveisi es reishis…” even if the fruit is brought by a shliach because shlucho shel adam k’moso, and it is as if he did deliver the bikurim. Tosfos disagrees and says the owner cannot read the parsha unless he personally delivers the fruit as well, as he cannot say "hayveisi". According to Tosfos, R' Yosi's chiddush is that even if the owner delivers the fruit, he still cannot read the parsha unless he also had harvested it or taken it from his house.

Why would Tosfos not apply the principle of shlucho shel adam k’moso in this case? I have an idea, but I’ll just throw out the question for now.