It looks like a problem related to the time-dependent nature of the imported geometry.
Yes it does because in playing around with it I found I could reproduce the issue with the file import node.
There is the option to either import as a sequence or choose a single individual file/frame.
I found it doesn't matter what source of bgeo's I use, it only depended if I choose a sequence or single file/frame.
I guess your solution is good, if that option was what it was intended for only? Otherwise there might be an issue if setting it to never is not an option for other case scenarios? I don't know since I don't fully understand by the description if this is the only case it was meant for.
Prior to your posting I had submitted a bug with a more simplified hip of the above one I posted. There I have stash node removed and whatever choice of bgeo one uses to see the effect, one can ‘toggle’ between a sequence or single file/frame on the import node to see the issue.
I included a simple set up just to generate some animated spheres to export and import for those curious.