So what you're really asking is "should there be a separate FPS limit for sidearms/close range weapons." And that's really up to you/your organizers.
We've had that on some [outdoor] fields that had structures and stuff that would present CQB-like conditions. If you're going to engage in those areas, or with X ft of someone, you need to use the lower power secondary weapon. Not unlike snipers (those that underwent the certification bit, anyway) are held to doing.