Before this, I must say this isnt meant to change your opinions or force you to dislike something, i see matchups as a fun comparison between characters mostly and i just think i dont like this particular comparison.

Now, Ill say potential wise its fine, good ol fistfighting i dont think you can go wrong with it, maybe you can argue armstrong's mech isn't utilized much here but you can just have saxton punch it apart it wouldn't be that jarring with how he is presented. 

Connections

I have my issues with connections, while its kinda hard to find written connections for this, imma talk about the ones i could find.

"two patriotic and wealthy CEOs who love to battle, and do so with their fists"

Now issue starts with calling Saxton patriotic id say, despite being a stereotype, he doesnt really go on tangents about Australia or how he'll make it great again such as Armstrong, this is a core trait of Armstrong as he constantly yaps about it and has actual ideology that relates to it in comparison to Saxton just…being a stereotype that isn’t really shown to give a shit.

“They have shady business practices involving arms dealing and mercenaries/assassins. Their companies have a significant presence in the southwestern United States (New Mexico and Colorado). “

I think this comparison feels wrong for an personal issue i will touch upon later but its correct enough.

"Both are empowered by metal which gives them incredible physical strength (Australium and nanomachines)."

Saxton being powered by australium isn't really focused or said outright, its just a general thing with Australians in comparison to Armstrong outright saying it.

its weird to me cause, Saxton is likely naturally strong for the most part from my reading, its shown that he kept his freakish strength always no matter the circumstance throughout the entire comics despite same comics confirming Australians instantly transformed back into skinny, physically non-threatening people whereas Saxton even after never receiving Australiums for years was still shown to be strong as an old man. (long after Australium pretty much disseappered from the face of the earth)

"Both have been investigated by the government. Hale and Armstrong loathe the weak, and believe that might makes right. "

First connection is kinda more of a tidbit so i will not yap much but i think latter connection is where its especially wrong.

Armstrong is a social darwinist which is a trait that ties into his ideologies he yaps throughout his entire fight and how he'll pretty much stomp through anyone weak to create his ideal America.  In Saxton’s case, its openly taken very comedically and not very seriously, its more so a way of showing how MANLY he is rather than planning to murder everyone in name of this ideology. Not to mention iirc, he directly works with people he calls weak (and is implied to be somehow fond of them from what I read into it). 

“Both the characters and series have a lot of memes. There is contrast in that Saxton Hale sends the TF2 mercs to fight a robot army, and Armstrong commands a robot army.”

i think these are tidbits than anything so i will not look deep into it.

Besides written connections I just have a issue with theming and general comparison.  Saxton does not match Armstrong’s genuine beliefs or role in the story, Saxton is not some big bad that manipulates war victims or kills billions of people, all of his overtly terrible actions are played for comedy than anything and he is more or less represented as just a quirky funny hunter man. Armstrong’s actions are legitimately treated as horrible war crimes they are (Loses company because of refusing to fight children VS Lobotomizes tons of children).  Saxton’s more serious traits and moments in comics such as him ruining his relationship with Margaret and missing her as a result or losing his company does not match Armstrong. 

Especially in last comics Saxton is humanized a lot in comparison to Armstrong being, comically evil unironically. I think it treats Metal Gear rising as too much of a “lol meme” game without addressing characters of both. 

On a more nitpicky note related to this, Wind of Destruction are like, legitimate war criminals manipulated by Armstrong for his cause whereas Mercenaries & others are similarly treated in a lighter, more quirky/humanized way and see each other as a found family (Saxton included). I don't think this is contrasts this is just being different characters.

Thats overall my issues with Saxton VS Armstrong. Thanks for reading, again this is just me giving my opinion on a silly little character comparison.