the snapshots won’t be usable as far as I know in that busy state…as long as you follow the guidance for removing them, you don’t actually have to delete them, if they are still withint your retention schedule, as long as they are free’d up as per the docs on the NOW site, the snapshot deletion process will remove them all eventually…if they are already outside of your retention period anyway, then its safe to delete them.
its normally based on something like SMSQL not freeing up old LUN copies within those snapshots properly as part of its backup jobs, it’s a realtively common problem, just something to keep an eye on.