The old man who was giving David orders was taking many shortcuts to figure things out as quickly as he could. He might not have known that the two nerds were making the beast with two backs, but he might have been fine with using the male nerd as a guinea pig for the goo. It's not impossible that he even believed there might be some copulation though the resultant accelerated pregnancy would have been a shocker, no doubt.
Yep, I know what was happening. I'm just saying I thought what was happening was dumb.