I just posted this... similar question
https://endless-sphere.com/forums/viewtopic.php?f=7&t=75850&start=25
I just finished a build today on an Electra Townie 7D. I believe the Fork you are referring to may actually be steel while the bike itself is Aluminum. Have you verified that your fork is in fact Aluminum?
I chose to use 2 Grin V2 Front Torque Arms (One of the reasons I went with the new Mac 10T is the side Exit cable allowing me to do this easily). That's half an inch of Stainless Steel plus the Drop outs. So I'm pretty confident.
Sadly I did have to file the Axle on the cable exit side. On the other side the Torque Arm slid right on. Crazy Chinese Quality (I know some day some Chinese person is going to get back at me for all my "Chinese Quality" comments by stabbing me in the neck)... but I'm not too worried because they will probably use a Chinese knife and it won't kill me
Also the Washers did interfere just a little bit with the cable exit. So I wrapped with a little extra electrical tape. I was worried that vibration might cause the cable to be cut by contact with the washer.
But I wouldn't run Aluminum Forks and any motor... Forks are cheap, Crashes... might not be.
As mentioned in post linked above... I was riding a Trek Mountain Bike with an Shimano LX Crank (Aluminum) and it sheered right off. The bike was almost new. Scared the Begeebus out of me. And introduced me to the concept that aluminum is not forgiving and gives little warning.
Surly Steel Forks ROCK!