I was thinking as I read that comment that it seemed unlikely you would not only (1) attempt to use companies' logos without their permission and without accurately representing the relationship, but also (2) get away with it

It is often in the contract or in the general terms of the commercial agreement so you have to watch out what you are signing. Especially if you work at a company which is somewhat known in the industry - the sales departments of SaaS companies start acting like sharks just because you use their product for some niche use-case on which the business doesn't really depend.