As with any sort of specialization, there is always a trade-off. Earning another degree (masters or PhD) makes you more specialized which tends to make you much more interesting to a very small number of employers and makes a larger pool of employers a bit more wary. But that's no different than, say, if you wrote a book or did something else to distinguish you. For the people that really want an employee with that exact specialization, it's great. For everyone else, the assumption is that the additional specialization would make you more expensive, less interested in the job they have to offer, and don't provide a lot of value to those employers. But these may not be jobs that interest you in the first place (hence the expectation that you'd be less interested).
People in industry are always a bit suspicious of people that have spent "too long" in academia without doing any industry work (it's not clear whether that's the case here or whether you have some industry experience as well). Fundamentally, there are often different outlooks between industry and academic pursuits. Industry, for example, isn't generally interested in innovation for innovation's sake, they want the results as quickly as possible. Academics are often seen as having their head in the clouds a bit in a way that makes it difficult for them to efficiently solve the current practical problem rather than the general class of problems it represents. Someone with 3 post-graduate degrees and no track record of industry experience is likely to raise some concerns on that front.
Finally, there is a question of whether the particular degree you're after adds a whole lot of value. Your existing degrees and your work on your PhD already indicate that you're likely pretty familiar with computer science and programming so it's not obvious how much you would really learn in a computer science program that you don't already know. As an interviewer, there's a good chance I'd ask you what you gained from the last degree program that you didn't get from the first two.
Personally, if you want to pursue a third master's degree, and assuming that you don't have a lot of industry experience elsewhere, I'd try very hard to design the program so that you can work closely with an industry partner on some real-world project that is something you'd be interested in doing after graduation. A more practical degree program would tend to help alleviate some of the concerns that employers would tend to have about someone that had spent that long in academia.