That this Caesar is Nero has been already flatly implied. Any readers familiar with the time of Felix and Festus would have understood this was Nero's era. So why not name drop? I'm no expert on the 5th (6th) Roman Autocrat (Dictator), but I've never heard of any taboo against using his name.
This, along with the inclusion of "Augustus" (Gk: Sebastos) at 25:21 suggests (to me) that Luke was deliberately attempting to honor Nero, because his writing was intended to defend Paul before Nero. Using the imperial title repeatedly and throwing in the superlative honorarium to boot?
It's no smoking gun, but it's absolutely something Luke would have been wise to do at the time.
Note: I just noticed this today, so if it's been discussed before feel free to enlighten me, anyone, though I'm sure the late-date advocates can offer some other explanation, if they haven't already. Personally, I will always believe the bulk of Luke-Acts was researched and