The typical joined Trill usually becomes joined in their early-to-mid 20s. Do those that are Starfleet officers typically go to the Academy then become joined, or become joined and then go to the Academy?
Would joined Trill be considered a security risk? They don’t take secrets to the grave, they carry them well past that. A loyal joined Trill might die leaving the symbiont (along with memories and secrets) to someone with less loyalty. Even in cases where the new host is loyal, do they automatically gain the security clearance of a previous host? Are there methods used by Trill to selectively remove classified memories from the symbiont?
Along the lines of the above, would a Vulcan Starfleet officer that has access to classified information be restricted from using the mind-meld with others not cleared for the same level of information? It seems like using it on unknowns or hostiles could be a major security risk.
I imagine Trill would consider any vows of silence taken by one host as binding upon them. even if it wasn’t legally the case (that’d have been an intreasting episode of DS9) almost all Trill hosts undergo considerable training etc. So that I imagine there are certain understood conventions such as “keep confidances etc”
I imagine that Trill are as much of a risk as anyone who retires from Starfleet. It’s not like everyone dies in uniform. They’re subject to whatever NDAs any other officer would be.
As for the symbiote being joined to someone who’d be a problem, I would hope the selective nature of the joining would rule that out.
Judging by the timeline seen with Jadzia, and the initiate she teaches briefly, Trill don’t become joined until their mid-to-late 20s typically - a candidate needs time and experiences to form a solid sense of ‘self’ before the joining to both ensure that they don’t get overwhelmed by their symbiont and to make them someone the symbiont wants to join with.
Even then, the point of “figure out who you are, then become joined” seems to ring true as a policy for joining in general, which is enough for me to reason that a Trill in Starfleet would graduate from the Academy and probably have a year or two of experience before they apply to become joined.
Of course, as Starfleet Academy doesn’t seem to have an age limit for entrance, there might be some joined Trill that discover an interest in Starfleet that wasn’t there before they became joined, and there might also be some that decide to drop out of Starfleet after becoming joined.