Here's a 14-50 that specifically says it'll work with aluminum conductors:
Extreme durability runs in the family. Premium materials, robust, uncompromising construction built to deliver. We are the one that works for you.
www.homedepot.com
Other than the HPWC install guide, which is very specific and says CU only(when connecting to the HPWC!), there's nothing to my knowledge saying you can't use aluminum in an EVSE circuit. If you have a reference, please share it.
Side note: even if aluminum is allowed to be used in a circuit, I'll never use it myself by choice.