Let me rephrase, then.
Every opportunity we have to push Gretaria is going to look like this one; some weakness with the Sydraxians that we could potentially take advantage of to get an edge in. It is very unlikely that we ever face a Sydraxian government that voluntarily releases Gretaria and invites us in, only one of Akuz's factions had that as policy, and only indirectly. Therefore it seems to me that the opportunity to go into Gretaria without worry will never occur.
Two, actually. One is egalitarian and democratic, so they'd have pretty big incentive to be friendly to both us and the Gretarians (even if that doesn't lead to Gretarian independence, at that point it's not like we'd mind), and unfriendly to Cardassia, even if their description doesn't state anything outright. The second is isolationist, including independence from Cardassia and for Gretaria. Add in a couple years or decades, and sooner or later it'd be pretty difficult not to get any opportunity to work our diplomagic; In the meantime they shouldn't be a problem either way.
Between themselves, the two hold two thirds of the potential ideals that could sway the kingmaking soldier/police faction, and the isolationists are described as credibly being able to overthrow the red/blue camps by themselves, even if they don't make some kind of coalition with the democrats, and even without counting anything we or the FDS can pull to covertly assist, however much or little that may be.
And if you don't believe me, then please at least believe Akuz herself, who'd be the authority on this topic second only to Oneiros himself, and who outright stated that things are looking pretty good for us there.
And we haven't even had the opportunity to see how the situation shakes out. Could be that they'll be at it for the next few decades, could be the reds retake power within the year, could be that one of the two factions preferrable to us does or an alliance of them.
We don't know. But we never will find out what could have been if we inadvertently give the reds the ammunition they need to shoot down their opponents.
If however, like you predict, this continues to go on for the next few years and we face the same choice a few years from now, then we
will have gained a lot of insight into the situation from sigint as well as our new contacts. From this we really should be able to tell wether or not a decision is anywhere within sight at that point, and if yes what that situation will be; We can still decide they're not getting anywhere and simply unilaterally affiliate Gretaria then.
Yet again. Since Lora the Sydraxians, militarily, are broken without hope of recovering for years. Now, politically they are equally broken, and even best-case for them and worst for us, their division isn't simply going away within the next few years. Any opportunity we have to take the Gretarians right now, we're going to have much the same if we just wait a few years.