What happens if a guest comes uninvited and is present at the time of the sunset on the eve of Eid al-Fitr?

Ayatullah Sayyid As-Sistani says that the host should still pay the Fitrah as an obligatory precaution.

However, Marhum Ayatullah Sayyid al-Khui was of the opinion that is recommended for the host to pay Fitrah of an uninvited guest.