'Science based' policy?

A 6 year old who recovered from COVID19 needs 2 doses of vax to eat in NYC restaurant: is it sound policy?

I saw this tweet today:

Marty Makary MD, MPH @MartyMakary

It goes against the data. Requiring a 6 y.o. who had covid to get 2 vaccine doses embodies the new pandemic of lunacy https://t.co/48KTsZKxok

James Lim, MD @JLimHospMD

@MartyMakary My 6yo who had COVID (I swabbed him myself, PCR+) in Nov can't go on a cruise until 2 wks after he's fully vaxed. He also potentially can't go eat in a restaurant in NYC. Where's "the science" behind that? And before I get flogged for being "anti-vax", please look at tweets.

It is an interesting question. First, is the technical matter. What evidence do we have that 2 doses of vaccination are necessary and risk reducing for a 6 year old boy who ALREADY had covid19 (and 1 dose of vax)?