You know, it can be true that the Steelers would have drafted Lemon if he was available, and also true that they really wanted Iheanachor once Lemon was off the board. It's also possible they used the entire clock to generate suspense at the home town draft. More likely when they say the opportunity to trade down was there, means the offers to trade down weren't that attractive. As per a previous post I made, look at what teams were giving up to move up (not much) and where they were moving up from (28 and later).
If there's a player you really like and also a couple of others you also like, you might move down a couple of spots, but not 5+ spots, and you might be willing to move down to get an additional second, but not to convert a third to a second, or a fourth to a third.