Because the data now indicates that wider tires are faster overall…especially on rougher courses.
Now, what you pick up in speed form wider tires will be offset somewhat (or completely) by a MTB riding position vs. being on the drops, but your comfort will also be significantly improved.
And you have plenty of time to train to make sure you complete the course before running out of steam. Then on race day, just make sure you pace and fuel yourself appropriately…you’ll be fine!!
I have a spot I unfortunatly have to sell. DM me if interested. I’m registered in the 200k open men division Current price is 320$, I’ll accept offers lower than that. I have also posted this in therift facebook page if you want to cross-check me