Yes. So much yes! Best specialist idea in a long time.
I would lean more toward Juan's tweaks for the specifics, and I'm not sure Sentry is the right spec to promote from, but it's a capability I think we've all wanted at one point or other. Making enemy subs go slower is a very nice touch and fits in beautifully with the lore, on top of making it an intriguing combination of intel-offensive specialist capabilities.
Actually, using Juan's slightly nerfed stats, I don't think it would need to be a promoted specialist, it would stand well as a first hire.