Not to sounds snarky, but in 50 years of doing this I have never had a tire blow off unless I mounted it wrong. The bead has to seat evenly. I tend to mount the tire, inflate to max PSI, and carefully inspect the rim to see the tire is hooked onto the bead properly. Usually there is a little line near the bead of the tire - and I check to see that is evenly spaced from the rim along the circumference. Otherwise, I haven't seated the bead properly.
To answer your question - tubeless tires are very tight in general (some more than others) - my Schwalbe's are so tight and stiff that I can't get them on some of my non tubeless rims at all. My Conti GP5000 are exponentially tighter than anything I've ever had in my life (32mm road tubeless). All traditional tires are floppy and loose compared to these two brands.
Yeah but he's doing an old-school ghetto tubeless conversion; back then tires were notorious for blowing off rims. But it begs the question to the OP - why not just save yourself the trouble and get a true tubeless rim/tire combo? Stuff is DIALED these days!