You are technically correct...
Any spellcaster has to have a hand free to handle material components or a focus in order to cast a spell with material components. When using an expensive component, they have to use the actual component and can't substitute a focus such as a staff or wand.
Normally that's no big deal, and only really becomes an issue if a caster who favors a focus, which they have in one hand, has something else in the other hand, and suddenly needs to manipulate a gemstone or some such thing. They need to empty a hand to deal with the expensive component.
However, an artificer is required to always have their focus (a set of tools or an infused item) in hand to in order to do magic, and there's no exception for when they're using an expensive component. So yes, an artificer is going to need both hands to cast certain spells.
...but it probably doesn't really matter...
But on the other hand, is this really significantly different than how your basic focus-using wizard or sorcerer deals with expensive components? Consider the scenario: My wizard has a staff in one hand at all times, because that's his basic spellcasting focus. He decides to cast a spell that requires an expensive component. Is he going to put away his staff in order to pull out a jewel? No, in most cases he keeps his staff in hand while he pulls out a jewel with the other -- he has a focus in one hand and an expensive component in the other, which is effectively the same situation the artificer is in.
If he had a torch in his second hand, he's going to have to drop something to free a hand to fish out that gemstone. Sure, the wizard could drop his focus instead of the torch while the artificer couldn't, but I think the scenario where you're A) in combat, so that the action economy matters, B) have both hands full already, and C) can't or won't put down a non-focus item, is rare enough that this particular Artificer rule doesn't really put them at any serious disadvantage as compared to other spellcasters.
...and it probably wasn't on purpose.
I doubt this was an intentional design decision. It seems more like an accidental interaction of two rules that each were meant to be merely flavorful on their own. I would probably allow an artificer in my game to use an expensive material component without having to also have a focus in hand as well. If I had to justify this from a story perspective, I would say an expensive component is something the artificer has prepared ahead of time, so any "working on it with my tools" has already been done during down-time, and it's fully ready for use.
But again, the distinction is probably not going to actually come up.