> I spoke with a rehab specialist and he mentioned that since cannabis is oil based, there is no physical withdrawal symptoms as there are with other opioid products.

Cannabis is not an opioid, and I don't think there is any indication that being oil-based has any impact on whether a substance has withdrawal symptoms. Also, while the substances of interest in cannabis may be in oils naturally and in the easiest extractions, they aren’t actually “oil-based”, anyway. So, whether it came from a rehab specialist or not, this seems to be multilayered misinformation.