[Edgemeal]

Would this (Lua script) work for you?

-- move time selection to cursor
function Main()
  local start_time, end_time = reaper.GetSet_LoopTimeRange(false, false, 0, 0, false)
  if start_time == end_time then return end
  local length = end_time-start_time
  local cursor = reaper.GetCursorPosition()
  reaper.GetSet_LoopTimeRange(true, false, cursor, cursor+length, false)
end

Main()
reaper.defer(function () end)