[Dridzt]

Actually after staring at it some more the whole thing should be able to be reduced to this
(if all you care about is hiding all chattabs)

local eventframe = CreateFrame("frame")
eventframe:RegisterEvent("PLAYER_LOGIN")
eventframe:SetScript("OnEvent",function() 
  local tab
  for i=1,NUM_CHAT_WINDOWS do
    tab = _G["ChatFrame"..i.."Tab"]
    if (tab) then
      tab:Hide()
      tab.Show = tab.Hide
    end
  end
end)

drycoded.