In this, you are both wrong. the word ειμι is Present tense, Active Voice, Indicative mood, and first person singular. verga is wrong in that voice is active, not passive; and you are confusing voice with mood.
Well, my response was less than perfectly structured, but I checked a conjugation chart before posting, and eimi is indicative, which as you say is a mood, but who cares, because the real question was active versus passive, so why would I put it that way, apples and oranges. Totally confusing. My bad.
BTW, please give me your opnion on the how the copulative nature of this verb affects voice. The article I referenced in the post to which you are responding suggests that at least some grammarians do not even make the active/passive distinction here, because as a copulative the verb describes a link between subject and predicate, and not an action per se. I am inclined to agree with this assessment, which is why posted it after noting that the voice was not passive.
And again, I was too hasty and hence unclear in how I structured my earlier post. Misunderstanding was inevitable. My apologies.
Peace,
SR