Salesforce (how on earth does Twitter have anything to do w/ Salesforce)?
Among many other things that SFDC and Microsoft Dynamics CRM are used for, handling customer service communications is one that has in the last few years been expanded beyond email and IRL interactions.
I don't know the SFDC world, but I work in the MS camp and one addition from a few releases ago was the ability to measure "customer sentiment", by searching through Twitter, RSS and Facebook feeds. IIRC Linkedin was in a walled garden and could not be read.
What some Microsoft Partners were doing, for example in the charity and higher education field, was to look for any signals that students/random people were so depressed or desperate that they used social media to announce their suicidal intent. There are other more conventional uses for this customer sentiment, related to avoid or contain customer service faux-pas that could become viral and therefore more expensive than to settle individually with one aggrieved customer.
The rationale for this sort of acquisition could include having more communications channel to what the CRM system can use (ticking another box for enterprise customers); ensuring that social media networks with 100,000,000+ users are not walled gardens beyond the reach of the graph and search facility of SFDC/Office365/etc.; Getting more behaviour and geo data for Azure/Google/SFDC/etc. to get better with their AI.
All else failing, just put loads of adverts under Bing management rather than Google's. IDK