That’s certainly one way to remove a shield.
There’s no explanation on why the Elysians just happened to have bomb components lying around, but it’s a good thing they did. There’s absolutely no way to get through that shield without the bomb. Technically, there must be some way to get to the shield projectors, because the Space Pirates somehow assembled it within the last month, but we’re never actually given a way down there so presumably Samus’s ship is not up for the passage. It’s just a shame the bomb wasn’t a bit stronger so we wouldn’t have to go down there at all.
While the first part of the battle is not technically on a timer (the welding is on a real timer), that health bar may as well be a timer. It has a rule where it’ll survive with a sliver of health once, but if you’re getting it down to a sliver of health then you’re probably not winning. What you actually need to do is down two ships: the rest of the enemies are just distractions. However, they’re strong enough distractions that Samus will die if you just totally ignore them, so I did have to actually take them out. This is where higher difficulties truly are Hard Mode, because enemies tanking hits is a major problem anytime you’re on a timer. And this is not the last boss fight on a timer, either.