On the medical benefits alone it seems obvious to continue giving J&J. The counter-argument I understand is that J&J's supply is severely limited due to manufacturing problems right now, so pausing it doesn't significantly slow down the vaccine rollout. There are a lot of people right now that saw headlines about J&J's manufacturing defects, and now this one death, and are convinced those are related. Visibly pausing something that is such a small percentage of the vaccine rollout might be a good political move.

Full disclosure: I took the J&J vaccine last Thursday, and would do so again right now.