Do you need 2 subs? Just take 1.
I'd agree with the drummer. Putting a little bass drum through the PA improves the sound of the whole band and when everyone can hear the bass drum, the timing of of the band tightens up.
If you want to make the drummer happier still, run a bass drum monitor for him.
I used to play with a drummer who bought his own PA, just for the bass drum, and 1 speaker which went between us at the back. Hearing the bass drum so clearly changed and improved the feel of the rhythm section. I was surprised ho much better we all played with just that one change. He then ran a feed from his PA to the band PA.