That is an interesting suggestion. Please note, though, that the Kares is not for the Kohen who offers it with the wrong intentions, but for the person who eats from the Korban -- even in the correct time and with the correct intentions.

Here are my thoughts on the matter, for what they are worth: When more Kedushah is involved, the desecration of that Kedushah carries a greater punishment. The reason for this is twofold: desecrating Kedushah is a bigger rebellion against Hash-m, and, in addition, any such desecration by nature suggests the acceptance of an authority higher than the One Who commanded us about this Kedushah, Chas v'Shalom. Thus, if someone brings a Korban, the epitome of "Avodah", and brings it with intentions that the One Who commanded us in Korbanos prohibited (i.e. he plans on doing the Hakravah or Zerikah or Achilah at a time when such is forbidden, presumably because it is more convenient for him), the Korban is Pigul. The one who brought the Korban put his own considerations above Hash-m's and did not subjugate his will to that of Hash-m.

Why is the Kares for the one who eats it and not for the Kohen? Perhaps the Kohen who puts his convenience before the will of Hash-m is not to be blamed as much, since he has personal reasons for doing so. But one who eats from this Korban shows that he accepts that the will of the Kohen (who offered the Korban as Pigul) is more important than that of the Creator. This is tantamount to Avodah Zarah.

(The commentaries explain that Pigul means "To'evah", disgusting. "To'evah" is the term used for Mishkav Zachar, which is also a misuse of Kedushah for personal reasons.)

Note that only Machsheves Chutz li'Zemano is b'Kares, not Chutz li'Mekomo. The reason may be because the latter is less of a rebellion against the will of the Creator, since Hash-m did, after all, permit Bamos (at certain times and with certain Korbanos).

Note as well that eating an animal that was sacrificed she'Lo Lishmah does not even transgress a negative prohibition. (Even if it was a Chatas, there is no unique prohibition which applies to the animal, as in the case of Machsheves Chutz li'Mekomo.) Dr. Moshe Kaplan (as I understood him) pointed out to me that the reason might be because Machsheves she'Lo Lishmah "uproots" the Korban from being what it was supposed to be, thereby invalidating it. When someone eats from it, it is no worse than eating from any Korban Pasul. However, a Machesheves Pigul is not an attempt to "change" the Korban from what it is. Rather, the Korban still retains the Kedushah of a Korban, in a sense ("k'Hartza'as Kosher Kach Hartza'as Pasul"), and therefore eating from it is considered a recognition and acceptance of the will of the Makriv. (Other possibilities are she'Lo Lishmah is not a rebellious thought, since the Kohen does have in mind to offer the animal as a Korban that Hash-m commanded - Y. Shaw.)

Best wishes,

Mordecai Kornfeld