The Narcotics Bill (amended) was enacted last year and has deleted the 20 year period and has added life imprisonment and/or 30 million KSh. This amendment is not consistent with case laws so likely won't be sustainable.
If they get a really good lawyer, they could argue for exceptional circumstance i.e., couple have impoverished history, victims of abuse etc. refer to elements in previous case laws which focus on the type/quality of narcotics e.g., this is not cocaine, motive based on serving the community for medicinal purposes, because this hasn't been covered in the statute. Basically paint the duo as victims, sufficient to convince a jury not beyond reasonable doubt.
If they want to crack down that hard on these networks then create jobs for youths, not put them in prison for life.
Also crack down on shipping industries which import/export drugs.
https://www.nortonrosefulbright.com/en-ke/knowledge/publications/8c3ba49a/narcotics-on-ships