Never turn down a sales lead

Agreed. It makes me wonder who he is lying to -- perhaps investors? Otherwise, why would there be any need to lie in the first place.

Plus, you can decline without being rude. For example, a lot of startups just arent set up to manage sales calls or leads, and to do so too early in your development might be more problematic than its worth trying. Especially, if you realistically expect the target to be only a mediocre one now, but a great one later. In this situation, and provided you can tell the person about your current development/business status, just thank them and let them know you are waiting for the right time.

Alternatively, you can always be vague without lying. "Thanks, I'll look into this". That doesnt imply any action, and it isnt deceitful either.

I think that rather than asking you to lie habitually, he actually meant that you should express gratitude in such situations. As far as social and business norms go, thanking someone for a lead and saying you'll follow up as soon as possible (even if that's unlikely) wouldn't be considered lying, unless you're being overly pedantic. =)

It's also hard to see how this advice wouldn't be the optimal behavior in most or all situations. Almost all the time, communication is as much about how the communicators make each other feel as it is about the information being communicated - hence the smiley in the previous paragraph. =) The advice in the article is just trying to point that out in the case of someone offering you a sales lead.