Don't tell him that. He's willing to get any vaccine at all and the world desperately needs to be vaxxed. If people want to take adenovirus vaxs because they feel its safer I say just let them.

I think what continues to surprise me (after talking about these for months now) is his underlying assumption that the third choice is a likely option. While the continued rate of spread seems to suggest to me that really we have a near binary option:

1. get injected with some vaccine soon, expose your body to a controlled amount of slightly noxious chemicals and hope your body learns how to eliminate them before they degrade on their own

2. contract COVID-19 soon, expose your body to those same noxious chemicals, plus a bunch of others that help it spread throughout your body and cause damage and linger, possibly for weeks or sometimes until you die

(excluding extreme options, like living alone for the next 5 years far from other humans, or dying of a mundane cause sooner)

Informed consent is very important in medicine for good reasons.