Again that is open to perception. It sometimes takes me a week to answer an email & often if its not super imortant, I'll put it aside to answer it later then it's forgotten. I figure if its urgent they will ask again.
Did Billy send one email, two or ten? Did he just ask basic questions or were any emails marked urgent? Did a day go by, a week or a month? Maybe Mr. Fong was out of town for 2 weeks & just got back. Maybe his wife just had a baby. Maybe his spam filter caught Billy's email or vice-versa.
It sounds like a 1-2 man show maybe, and if that's the case depending on the content of the email & how much time transpired indicating "I never received a response" might be interpreted as "I never received a response in my acceptable timeframe". I can go on and on. :-)
This is another reason to be thankful Billy took his time to do legwork, but if you have further concerns one must do their own work to base a trade decision on because perceptions vary from person to person. Taking two days to answer might be too long for some, whereas I would be "What's the hurry Bub". :-)