Who is "asking" him to play 1B, high school or club? I've never heard of a high school coach asking, only telling. IMO, you do whatever it takes to get At Bats. My son was a C in high school, but coach wanted his bat in the varsity lineup sophomore year and moved him to 1B. In my biased dad opinion, son was a measurably better C than the starter, but that kid was an established leader on the field. Son ended up staying at 1B with his high school team through senior year. However, he continued to play C for his club team, and was recruited as a C. And, he would have gone to college as a C if not for a knee injury (he played 1B at a D3).
Just be aware that 1B can be the toughest spot on the field to earn. Not only are you competing with all the corner guys, and the DH, but most of the lefties on the team (including pitchers in some cases).