Assad has used them several times before. Why didn’t he have everything to lose and nothing to gain then?
Flashback 2013:
UN Investigator Claims Evidence Syrian Rebels Used Sarin Gas
https://www.thenewamerican.com/world-news/asia/item/15308-un-investigator-claims-evidence-syrian-rebels-used-sarin-gas
U.S. Military Document: Syrian Rebels Had Chemical Weapons
https://www.thenewamerican.com/world-news/asia/item/16577-u-s-military-document-syrian-rebels-had-chemical-weapons
Syrian Rebels Fire on Civilian Protesters
https://www.thenewamerican.com/world-news/asia/item/15449-syrian-rebels-fire-on-civilian-protesters
Top Syrian Rebel Group Merges With Al-Qaeda in Iraq
https://www.thenewamerican.com/world-news/asia/item/15065-top-syrian-rebel-group-merges-with-al-qaeda-in-iraq