I have no affiliation with the project, but shorter validity is theoretically more secure.

So, no, it's not about the price. That said, if the above was not the case and I was pulling off a scam this elaborate, I'd not hesitate to cough up a few bucks to cover my tracks.

I hope this helps

Edit: I found a link so you don't have to take my word for it (again, I have no affiliation with THIS site either): https://www.globalsign.com/en/blog/advantages-of-short-lived-certificates/