Sama's point is that because so many people are saying tech stocks are expensive then there isn't the mass delusion required for a bubble.
A market can be overpriced when the consensus view is that stocks are more valuable than is actually realistic. When more sober judgment sets in, stocks go down to more appropriate levels.
In contrast, a bubble is when stocks are going up, and so everybody wants to buy stocks because they're going up, and so stocks continue to go up because everybody's buying them, and so people continue to want to buy them because they're going up. It's not a bubble until you get that positive feedback going.
I agree with your point about "cheap" being used more traditionally in that an investor may think the price they're paying is high compared to what the stock price should be based on fundamental analysis. That situation isn't the same as a bubble (although it might happen in a bubble).