And people always assign more power to magnuson moss than it has, or assume the reach is farther than it is. In general, magnuson moss protects people from having the entire car warranty voided because of unrelated parts, and also protects in the situation you said, where an aftermarket part is built to the SAME SPECIFICATIONS as the OEM part, it can be substituted in.
So, A manufacturer cant see you have to buy a specific air filter / oil filter brand (from them, for example), if there is an aftermarket part that meats the SAME SPECIFICATIONS.
It also protects one in the case of (for example) of installing an aftermarket seat, and then having an issue with your engine.
When people discuss "void the warranty" many of them make it sound like the entire car warranty will be voided, which isnt usually the case.
In THIS specific case, if one installs spacers on a vehicle, then there is a warranty problem that has anything to do with suspension, ride, etc, tesla "could" state that the spacers are the issue and refuse to cover it. Doesnt mean they will, it means they could, so there will be NO "definitive" on this, regardless of OP looking for such.
Magnuson Moss would not protect anyone in this specific case, either, as modification of suspension from OEM is grounds for a manufacturer to not warranty said suspension, however, if one then had a claim about their touchscreen, or seats, or anything not related to suspension parts, that warranty would not be impacted by aftermarket suspension modification.