Its hard to keep perspective with the "lack of knowledge" on todays modeling technology and the stigma others may have... So in the vein of keeping the good blood between you and the bass player here are a few more "common sense" issues that need to be pointed out.
1) If you played a venue without a appropriate monitors you are already screwed... your vocalist is the one that everyone should be the most concerned about if that is the case... I haven't played a venue without monitors in a long long time... even the smallest clubs have them. if they don't, you need your own, or go IEM.
2) I get the fact that he may be used to the Sound Pressure Levels pounding on his chest, but once you guys have worked on getting your levels acceptable (meaning- just above the drums) your sound will improve immensely.
3) Like others have pointed out... clearly, he is in the dark with how prevalent modelers are now in live situations...point him at a few of the bands and add this guy to the list -Richie Castellano of Blue Oyster Cult.
4) This has been said as well, so just repeating good advice- get a good monitor for your self... I went with the L6 L2M, there are more affordable options but this one works great... I can place it behind me like a cab, but I prefer to use it as a monitor and go direct to the house PA. It works fantastic, and I have never heard one of my band mates complain about my levels (or lack of amp). I used to blow their heads off with a Marshall 1959... I just think they are all thankful now!