Problem with callvote is that all callvote menu items are handled directly by the game engine, either by "uiScript" or by "exec callvote". We can not intercept the commands in a server script like most other menus. Currently you have limited control over the callvote option by setting callvote delay in mapcontrol.cfg. We could enhance that by using the X4 system instead, which looks like this:
//******************************************************************************
// Call Vote control
//******************************************************************************
// 0 = disable (g_allowvote is not controlled by X4) (default)
// 1 = enable mode 1. callvote disable, then enable after delay
// 2 = enable mode 2. callvote disable, then enable for x seconds, then disable again
// 3 = enable mode 3, callvote disable, then enable for x seconds, then disable for x seconds, and cycle
set ex_callvote_mode "0"