Conventional wisdom would alter all similar rhythms in the entire piece to the shortest note value, but that particular performance practice has never really been backed up by evidence. And it asks the question of why Handel would write out that particular rhythm at all in the piece if it were "understood" without. He goes to the trouble of writing sixteenth rests in one additional spot:
Given that this rhythm is explicitly specified twice, yet nowhere else, I'm inclined to take Handel at his word and play it as written. Nonetheless, I still don't feel "sold" on how it operates.