I was assuming from your code that you were using a pre_get_posts filter and that is where this code would be added if I used it.
Honestly, I would probably not use it, it means that your main query will require 3 queries and this will reduce performance. I would likely just show current and future events archive page and then build a separate page for showing past events. I would only do this if the client insisted and first I would explain that there was a potential for this slowing down the page load and make sure they understood that before I did it.
