Not likely about the tac nukes.
1) The before and after photos show no visible damage to a nearby building, unlikely if it had been even a small nuke.
2) If it had been a nuke, Syria would have opened the site to international inspection, the radiation evidence would have been incontestable and irrefutable, and the site would have contained no evidence of any Syrian mischief due to the totality of the destruction. It would be perfect to discredit their enemies in the court of international opinion and a great propaganda victory for them.