Highly doubtful, if not completely preposterous.
Phase cloaks - illegal (unless they wanted to face a two-side war against the Romulans as well)
So? And assassinating Romulan Senator Vreenak wasn't illegal? Plus, as we saw in "The Search" the Romulans were willing to negotiate an agreement where the Federation could legally use cloaking technology.
M5 computers - 100 years out of date (also hugely flawed at its conception)
And 100 years of R&D should have been able to overcome some of the issues, like not using a mentally damaged individual as a template for the M5 (or would that be M10 at that point).
Or, what about armies of androids? Besides Data we had androids from Planet Mudd and also the Andromedan Androids from "What Are Little Girls Made Of?" Or combine these technologies for advanced starship cybernetics.