That is possible, but certainly the image of the drops of blood are important to Luke, otherwise he would have simply written "katabe epi ten gen" [fell on the ground]. It seems to me that Luke--if these two verses derive from the sacred author--wanted to direct the audience's attention to the reality of the blood.
Mm, well, it's hard for me to give that value to hosei. In fact, I'd say the opposite: if he meant to say it actually was blood, he'd've dropped the hosei. It's difficult to see its point, if it weren't that the good doctor (on the common reading) was saying that it wasn't blood, but was thick like blood.
Otherwise, you'd have to ask yourself what Luke could have been expected to do. "He sweat great drops that, while like blood, of course were not blood..." would be a bit turgid.
But you still win the prize for correctly ID-ing the word in question.
Dan