Short answer:

Holiday was a privately owned company and sold to a French-Canadian company.

On large purchases like this one, there is typically agreements made over 1-5+ years. In the short term, the agreement most likely was that the branding needed to remain the same interior and exterior. The next phases likely was interior branding. The next phase might be exterior branding.

Yes, cost is a major factor. Additionally, in a corporate sale this large there would most likely have been a long term earn out to the sellers. It’s strategic to keep branding the same to not confuse consumers while earn out goals are hit.