Because it is more likely than not to take place. Not only UK but other nations as well. Until Israel comes to its sense and shows evidence that it wishes to join the international community again. Otherwise, these IDF generals will have to be personae non grata.
Bennett, Deri expected to resign from Knesset, remain in cabinet under new 'Norwegian Law’ (Haaretz)
from the article: Deputy FM: Arrest warrants harming Britain-Israel ties