Dear Cs,
Citations doesn’t take it out of the realm of theory until those sources can tell us why it is so. And these sources are all after the fact of lag baomer, so they don’t signify that this was the purpose. It’s just the way of explaining what is already custom. That is theory. I didn’t celebrate it growing up, and I still don’t.
The Rebbe was adamant that lag baomer was not the day rashbi died. it’s a misspelling. It reads, the day he rejoiced. And there is no mention of it in the Zohar.