Yup, was definitely expecting that.
He knew the first question was rhetorical, so he waited for the inevitable follow up. When she asked, all of his planning went out the window. This was his mentor, one of the only people who was basically contractually obligated to help him. Maybe she wouldn't be rooting for him (she was from District 1 after all), but she wouldn't put her career as a mentor on the line just to screw him over.
So, he figured the best thing he could do in this moment is be honest.
"This... this wasn't a spur of the moment decision," he started, rubbing his hands together anxiously as he tried to balance between looking her in the eyes to show he was serious and looking at the floor for his own comfort. "I've been thinking it over ever since I was told I wasn't the choice, which... yeah, been about a year now."
He sighed before he continued. "You've met my teachers, ask any of them; no one can beat me if I get my hands on a longsword. Literally no one in that arena has a chance if I do. But... yeah, I'm fully aware there's no guarantee that I'll get one, but I'm not total shit at other weapons, like what's wrong with having a specialty? I was even better than Halcyon before he made it into the arena, and people still fucking loved him."
Halcyon's death was only during the 73rd games; she probably remembered him. Brilliant, charming, good at every weapon he got his hands on, but Silver at 16 could still beat him sparring, so didn't that say something about Silver? Shouldn't that have given him some credibility?
"I just... this was my last chance, alright? What was I going to do with my life if I didn't compete? All I know is how to be a warrior, and a fucking good one. And I hate kids, so teaching is off the table."
He took a step forward towards her and met her eyes and didn't let them go; he was going to make this point as clear as possible. "I will do everything possible to win. I'll do everything you tell me to do. I may be a warrior, but I've never gotten a chance to prove it and you did and came out the other side, so you know more than me. Fuck, I'll hang off of every word you say if it'll help you be more confident in my abilities, just..."
He trailed off as he took a seat in his chair before sighing again. His voice was quieter as he continued. "No one said goodbye to me. Not what few friends I have, not my parents, no one. So I know I'm ultimately alone in my belief in me, but... I hope maybe I have one mentor who's willing to give me their guidance. Because if I really am as unprepared as they said, well... my only shot is going to be listening to you guys and somehow getting sponsors to like me."
It was at that point that he looked up and waited for a response to his little monologue; he hoped his sincerity was showing.