No, it's not the “technically correct way”. It's true that some style guides recommend something like this (but always, AFAIK, more limited); e.g., the New York Times style (and Chicago style) uses apostrophes for plurals of abbreviatiins formed with capital letters and periods, and plurals of single letters. [0] AP, on the other hand, only uses apostrophes for plurals of single letters, but not for abbreviations/initialisms/acronyms. Most British styles I've seen don't use apostrophes for plurals at all, IIRC.

[0] https://afterdeadline.blogs.nytimes.com/2010/04/13/faqs-on-s...