The recruiter has numbers to fill and is pushing him to the mechanic route. I'd tell him to stand his ground with the 03 job or find another recruiter. I met enough mechanics while I was an 0331 and I had to do the work on our vehicles ourselves. Just because they have a mechanic MOS doesn't mean they know what to do, same as an 03 MOS. Infantry MOS's help a lot for contracting afterwards and they experiences they may or may not get; just opens up the opportunity and ability for other jobs and credentials.
This. First time I went all they had was 13 series, and I ain’t no fucking gunnbunny. Literally20 Mins later they had, 11, 19, etc etc.... all I wanted was to be a K