I don't think this was a plea to developers to not sell up, I think it was a plea to people to support small companies to make not selling up a more appealing option.
Ehh, maybe the last sentence implied that (though it could be read both ways), but most of the article read like a humble brag about Instapaper being successful enough that it doesn't have to bother with this type of situation. That's all well and good, but it sort of rubbed me the wrong way.