Avraham Sacks asks:
Why was R' Yehudah not concerned with chataos whose owners have not certainly died?
Avraham Sacks, Ramat Beit Shemesh
The Kollel replies:
Shalom R' Sacks!
Great to hear from you. I hope I understood your question.
If so, the answer appears to be because as long as we do not know that the owner has died, the rule of Chazakah tells us to behave as if he still remains alive.
I hope this helps!
Warm regards,
Yishai Rasowsky