If you plan on playing live, You will need something bigger even if you run it straight through the PA.
Probably not cool to demand the guitarist adjust his EQ to suit you...
We don't know what the guitarist was doing.
We don't know that the OP was *demanding* (that's a heavy word) anything.
I have asked guitarists in particular to change the onstage EQ, in particular their low end, quite a a few times, because it was messing up the whole sound onstage. I've asked people to turn down. Why not? I've also been asked to change things. When we're thinking of a band mix, it doesn't work very well if people get all precious "but it's my sound".
In fact, 8-9 out of 10 times anyone says "it's my sound", you're dealing with an uncompromising diva... so whenever I hear it, I see it as a red flag and keep my eyes open so that I don't get caught in drama, as it is often in the air after hearing those words.

