Help translating この姿なら異国人も怪しまれない. Why も instead of でも?

Question

この姿（すがた）なら異国人(いこくじん）も怪（あや）しまれない is a phrase said to someone disguised as a catholic missionary in medieval era in Japan, so he is not suspected by having a western face in the asian country.

I saw a lot of questions here about も vs でも, but generally speaking, the answer of the questions is that も means "also" and でも means "even", with the も particle playing the role of the が or を particle, including a subject or object in a list to interact with the verb, while the でも particle ephasizes an element on a list as being against the odds.

But in the phrase この姿なら異国人も怪しまれない, using that logic, も does not seem to fit. It does not makes sense if 異国人 is a subject of the passive form of the verb 怪しむ, because then 異国人 would be the person being suspected by someone, and not what someone is being suspected of, what makes more sense by the context.

An user in another japanese language forum translated it as "with that outfit, you won't be suspected even being a foreigner", what for me would make sense if the phrase had a でも instead of も.

Answer 1

異国人 is the subject of the verb 怪しまれる, i.e., 異国人 is the one being potentially suspected by someone else. この姿なら異国人も怪しまれない is simply この姿なら異国人は怪しまれない with は replaced by も. The object of 怪しむ can be either a person or a property of a person.

この姿なら異国人も怪しまれない。
(Japanese people won't be suspected because they are Japanese, but) also foreigners won't be suspected if they look like this.

この姿なら異国人でも怪しまれない is also perfectly fine, and the difference in meaning is subtle. If you had explicitly asked for a super-literal, word-by-word translation, the user in the other forum might have given a different translation respecting the difference between も and でも.