Yes, they could put red crosses all over, but for some enemies this means nothing, just makes them a more desirable target. I guess they're allowed to engage if their patients or their own lives are in danger, but not engage in combat. It would make sense for them to stay out of the fight because they're the ones who have to deal with everyone else getting wounded.
Since you know what a combat medic is, then you can google the term to see for yourself that they do carry weapons.
Here's an example (from the US military):
"Corpsmen and medics with combat troops carry a double burden. They do everything that Army soldiers and Marines do – although officially noncombatants, they are authorized to carry weapons to protect themselves and their patients – until a soldier or Marine gets hurt, and then they have to become lifesavers, sometimes under fire." https://www.ocregister.com/2006/08/04/medics-carry-a-double-burden/
Another article states he was a dual citizen. From what I understand Ukraine requires people who become citizens to renounce their previous citizenship within two years. He may have become a citizen in order to serve in the military so therefore would eventually have renounced his Canadian citizenship.
Not sure that he's being misrepresented as a medic. You're basing this on the fact his holding a gun in some pictures?
Thomas: "I think it is always worth it to stand on principle--no matter what the ultimate goal is. Wrong is wrong, even if it was over a penny."
Kroft: "Thomas believes the real issue being fought over during his confirmation was all but unspoken."
Thomas: "The issue was abortion. That's the issue today. I mean we can-"
Kroft: "This whole thing was about abortion?"
Thomas: "Yes, that was the elephant in the room."
Kroft: "In what sense?"
Thomas: "That is the issue that people apparently are so upset about that, uh, you determine the composition of your Supreme Court and your entire federal judiciary, it seems now."
Kroft: "Your opponents were afraid that you might at some point rule against or overturn Roe v Wade."
Thomas: "I have no idea what they thought, but they knew one thing--they weren't in charge of me, so I wasn't going to do their bidding."
"It's fascinating that people, there's so many people now who will make judgments based on what you look like. I'm black, so I'm supposed to think a certain way. I'm supposed to have certain opinions. I don't do that. You don't create a box and put people in and then make a lot of generalizations about them." (60 Minutes interview in 2007)
You're more outraged by this than a child dying because of the vaccine?