SXF seems well off route to Bratislava. Looking at a google map I would have expected them to be closer to HHN than SXF, assuming a diversion into a RYR base would offer better & knowledgeable ground service: also a base captain to represent RYR's interests in any immediate action & follow-up.
Looking at the flight tracks for this route for the past week on flightradar, it appears that the route crosses Germany some distance north of HHN. The aircraft was already some way past HHN when the diversion started (near Erfurt/Weimar), therefore diverting to HHN would have meant having to turn back. SXF is not too far off the planned route and did not involve having to turn back. The track shown on flightradar indicates they were probably a bit closer to SXF than to HHN anyway, and SXF itself is closer to Bratislava than HHN is. Also, there is a police presence at SXF (this may also be true for HHN, I simply don't know as I have never been there) and it is a RYR base.
I was wondering, in an incident like this which involves a diversion, at what point are pax informed (a) that a decision has been made to divert, and (b) where they are going to? I.e., would the announcement just say "right, that's it, we're diverting", and only tell pax where they are after landing?