Front brake rotor is loose on 2005 Toyota Sequoia

What holds the front brake rotor in place? Driver side is loose and tilts when wheel is removed which caused inside rotor wear wheras the passenger side is fixed and doesn't move at all.

Asked by for the 2005 Toyota Sequoia
The brake rotor is a "floating" brake rotor. This means that it sits flush onto the hub, but does not get fastened down by anything other than the wheel as it is secured with lug nuts.

Suggesting your drivers side is loose and passenger side is fixed is merely incidental and doesn't mean much, because with the wheels torqued down, neither rotor can be "tilted".

How does the rotor tilt with the brake caliper securely mounted over it? It certainly can't be tilting far...

"Inside rotor wear" is caused by brake pad wear out. If the inner pad wears out before the outer pad, typically caliper slides are sticking and need to be cleaned and lubricated.