One person, out of the 6.8 million who have gotten the J&J vaccine, died from blood clots. A second is in critical condition.
Yes, your risk of dying from COVID varies with age, but not to that extent. Even among children, the death rate for COVID is an order of magnitude over the 0.000015% to 0.000030% chance of death it would have to be for the decision to stop using the J&J vaccine to make sense, based on the numbers we're making that decision based off of. Among the people who are actually being blocked from getting the J&J vaccine (e.g. mostly 20s/30s/40s adults), the decision looks much worse.