try to prevent that.

I agree, currently tegirdy weed is everything to Randy to the point of not caring about his family, thus he thinks without tegirdy farms he is nothing and would try to stop Stan from erasing tegirdy farms even though it would revive Sharon and Shelly.

He would go 100% insane.

I don't see him trying to prevent Stan from erasing Tegridy Farms. But I would see him trying to get a partner to restart his weed business and later gets double-crossed by said partner.