Picking kids out of the hallway is not a good idea. If you want to have the kind of book a 5A school should have, non-drummers will either destroy that book into shambles, or make the line water down a lot.
The OP's line tentatively has three snares, two tenors, and two basses for next year. They just need a couple of people to round out the bass line, not step into the snare line. Complete newbies can be effective bass players if parts are basic enough and they have decent rhythm and work ethic.
In the short term, it's a positive because you don't have to move people off snare and tenor spots to fill the bass line. You can keep the notes in the book and still have enough people playing 'em to project.
In the long term, it's a positive because you've got rookies who'll get on-the-job training they can apply in future years. If you're only getting one middle school recruit a year, who's going to man the snare and tenor lines in three years?
If you have quality players right now, I'm sure you'll pass fine. A clean snare line is always better than a large snare line. A twenty person line would always be nice, but my school only has twelve battery members. We get by fine.
There's a huge difference between your twelve and his seven. Your battery is almost twice as big as his entire line. When you're at a school that doesn't have enough bodies to field a full line, you've gotta scrounge up talent wherever you can find it -- for now
and future years.
Recruit middle schooler's who have percussion experience... If your fielding a line for the field, it's not just the line your jeopardizing with non-drumming students, but the entire ensemble.
Yeah, I'm sure Mike McIntosh's old school regrets letting him switch from saxophone to dabble in percussion. His lack of drumming ability must've "jeopardized the entire ensemble".

...and I can probably come up with about a dozen other examples off the top of my head who had never drummed before joining their high school, college, or drum corps line.
Or for another example of non-drummers stepping into a line and contributing, check out
Springstowne Middle School. It's not like there's a feeder program for middle schools, but they somehow manage to teach their rookies how to play.