Google is well known for the acquihire. They aren't Berkshire Hathaway, they aren't just assembling a portfolio of companies. They have their own product plans, and generally buy out other companies as a way to get pre-built teams with the right specialties to accomplish that.
Also, it's very unlikely Google wants to be in the incident response consulting space: Google entirely hates any line of business that can't be automated into a smooth profit paste. Flying security professionals out to clients isn't in their DNA.