It was exactly the wrong behavior for a party that always existed more as an idea than a political force. National leadership has occasionally been more successful. Jordan's Abdallah took steps toward creating a pan-Syrian state in the 1930s, but these eventually came to nothing. But Asad is not kind of patron anybody would want, and his nation is one nobody would want to join. Unfortunately, the goal of a larger Levantine nation tends to get lost under the dream of Arab unity.
Arab unity is a more grand idea, but mostly because it is so patently impossible.
Nobody takes seriously anymore the idea of a nation that stretches from Morocco to Kuwait. At the very least, the Levant presents a better argument for unification than does Europe. Which may be why unity, despite opposition from virtually every organized political force in the region, continues to grow. Between Syria and Lebanon, the job of unification has, for better or worse, mostly been accomplished. It's hard to imagine either country going back to the state of quasi-sovereignty that existed before the Lebanese war.