Well - having a script do bulk changes is not unreasonable and easily doable within JavaScript. The question if this should be done to 25.000 nodes is more a question of side effects this would have. It would create a single transaction where all those 25.000 nodes have been marked as updated. Whenever SOLR is then tracking changes for index update, this will be a significantly "larger than typical" transaction, which cannot be split up within the SOLR processing. Depending on the resources available to SOLR, this can cause the index process to take noticably longer, and thus potentially introduces lag in your indexing process. Also - depending on the SOLR / Alfresco version used, handling path changes in indexing can be quite expensive (due to potential update cascades).
Typically, the recommendation for bulk operations is to keep the number of nodes affected in one transaction to a two-digit or very low three-digit number.
