I agree with this decision. In my opinion, I think they should also reban the Quickie, the Loch n' Load (yeah I get it, Demos need more variety but I don't think these weapons are balanced), the Cow Mangler, and Jarate.
Quickiebomb Launcher has got a lot less clip size than stock but the increased sticky damage and extra range you gain from it is huge, not to mention the shorter fuse. It's basically good for most situations now, and while it only has 4 stickies before needing to reload, it gives Demoman immediate extra effectiveness in both closer ranges and longer ranges, being able to defend himself easier and faster on close range despite the damage nerf, which is a questionable tradeoff from a balancing point of view, to being able to sticky snipe faster, further, and with much greater damage and speed. When a weapon needs to cut back half of its stock counterpart's clipsize at an attempt to "balance" it (pre-nerf Loch) you need to start questioning if there's something wrong.
The Loch n' Load. It makes pills way easier to hit, which is huge. The fact that its projectile travels straight without spinning also makes the effective projectile speed gain from the weapon greater than 20%, while also negating most of the slight random deviations in range/accuracy due to the spinning projectile of stock. Losing one shot and rollers for this much extra accuracy is not enough of a penalty.
The Cow Mangler is now pretty much a straight upgrade from stock for roamers. This weapon is really hanging on a balancing edge. Infinite ammo with negligible downsides for 6v6 play, and I know it sounds stupid but the charge shot will actually see some use now, especially in lower divs to make some absolutely bullshitty out of nowhere shots which deal way waaaay too much damage. Think about every choke situation where you'd be eating a few, normal rocket spam shots and replace it with a Cow Mangler charged shot. Yeah, no. This one is hard to balance because the former hidden reload speed penalty made it worse than stock in almost every situation, but now it's kind of the other way around.
Jarate. It might be tough to get into a position for a good piss soaking going against coordinated team play in most situations, but if/when it hits for whatever reason it is a massive advantage. It is also not hard to use either. And the drawback? There isn't one, in essence. So it should be banned, instead of increasing Sniper's viability/power even further.