Here's a discussion of your topic:https://weldingweb.com/showthread.php?36555-dc-welding-aluminum-ok-with-mig-but-not-tig
I don't see a clear answer there.
No offense intended but I don't get why anyone would buy an expensive tig machine that can't do a big part of what tig is for, welding aluminum. One of my neighbors has a DC tig machine and it can't weld aluminum. He brings me his aluminum welding. I've had a Miller Synchrowave 200 for about 10 years.https://www.bakersgas.com/MIL907308.html
It's is an AC-DC tig-stick machine that cost me $1800 including delivery to my front door. I gave the AC buzz box that it replaced to one of my sons. I find that the vast majority of the tig welding I do at home is on aluminum. An example is the aluminum dog carts I make for my wife's competition in a dog sport called "Drafting". At the higher levels of the competition the cart has to be loaded with weight equal to the dog(s) weight, NOT including the weight of the cart for the "field" parts (steep up and down hills) of the events. So a light cart is a competitive advantage. Another example of aluminum welding is on various cart projects like this cold air intake ducting. Only rarely do I tig stainless that uses DC current.
I found that changing the tig ceramic cups to gas lenses improved the quality of my tig welds. I'm an amateur, not a pro, so I'll take every advantage I can find.