they bring up a valid point: libreoffice is (in their opinion) harder to use and probably lower quality, so reports are harder to write and taking away time from more important things.

in my opinion libre office is absolutely good enough for this use case and thus not taking away significant time from other tasks. furthermore, the austrian armed forces are free to contribute to the project to improve the perceived paint points themselves.

on the other hand microsoft products are closed source and probably upload data to datacenters outside the customers (i.e. in this case, the militaries) sphere of influence. this may include the data (for storage and or AI training) and meta data (for advertising and telemetry).

microsoft may even silently introduce or reactivate (after they've been declined) those options after updates (don't quote me on this, but i think i remember this happening at least once).

microsoft apologists may argue that this is only the case for improperly configured corporate deployments, but as the software is closed source nobody can really be sure and if it's that hard to get right, it's a security problem in itself.