Hiring manager says org chart is flat, but LinkedIn says otherwise. What to do?

Two weeks ago I applied for a Senior Software Engineer role at a great company, whom I've just received a verbal offer from. They've met my compensation requirements and passed my culture test.

What concerns me is that the hiring manager asked if it'd be a dealbreaker for me to join the team as a Software Engineer rather than a Senior Software Engineer. The hiring manager explained rather briefly that the company is a rather flat org that doesn't really hire seniors.

But upon searching LinkedIn, I found 3 Senior Software Engineers working at this company (the engineering team is only 9 people).

I don't mind ditching my senior title (I've been a senior/lead at my last 3 workplaces). I just want to know the truth about why they didn't offer that title to me when there are clearly employees at the company with it.

How do I bring up my concern to the hiring manager?