That’s not a valid analogy: everyone knows that the billboard is separate from the shop renting the space below and Coca Cola doesn’t pay the porn shop to drive traffic to their ad. Twitter has revenue sharing and also uses that revenue to provide free services so there’s no way for an advertiser to avoid their money benefitting the extremist groups who use the service. Coca Cola paying for the billboard on the roof doesn’t mean the porn shop isn’t paying rent.
The porn shop is also unlikely to have anything on the front of their shops which is even remotely comparable to the tweets causing advertisers to leave. For all that religious nuts go on about it, porn is mainstream even in conservative areas and the ads will talk about pleasing your wife, not harming anyone. If they put up ads talking about how mixed-race sex should be punished or saying that women should be assaulted, the comparison would hold up more - and so would the reaction as they lost their business permits and lease.