Guide doesn't mention PSN at all nor preinstalled title. I'm 100% sure I didn't have preinstalled official titles and fairly sure I signed in to PSN after the jailbreak, not before.
One thing with the guide worth noting is when you're at page 4, Section IV - "Downgrading" you could follow the substep
- If you are currently on firmware version 3.65, proceed to Installing Ensō (3.65)
and bypass anything involving Modoru completely if you're planning on staying at 3.65.
I was late in Vita bandwagon as well, bought my phat jap original just year and a half ago. It was premodded with 3.60, but the modding included lots of extra and unnecessary fluff (hey I have 2 Amigas, why I should bother with UAE??? etc.) so I just returned to 3.60 OFW and started anew. My PSTV which I bought after falling head over heels in love with Vita was preowned but not modded, nicely on 3.65 OFW.