be inferior (but cheaper OP wise)
This is not a functional balance option in Starsector. You can always fit smaller number of more efficient and more expensive weapons, instead of filling all the slots with garbage. A weapon MUST be "best in slot" somewhere to be worth including in the game.
A good comparison would be Hammers vs Reapers. Technically Hammers are inferior, but there are still situations when you want to use Hammers over Reapers for one reason or another. Light Mortar vs LAG is another one.
Mining Blaster vs Heavy Blaster though? With the change they no longer fill the same role exactly, and there's far too many situations where Mining Blaster (in the form shown in the tweet) is just straight up superior to the Heavy Blaster in most metrics (specifically when it comes to phase ships, which should be the last ships you expect makeshift weapons on).
By the by, Hammer torpedoes didn't always have the "ubiquitous because of uses found by miners" line, it got added because I complained that Daggers shouldn't be using Hammers (which was planned to replace Reapers on Daggers at the time, thankfully that never eventuated); so it got retconned into a military weapon that became popular with civilians for non-military purposes.