The Astros have another aggressive buyer in the division in the Angels
Everything mentioned before about not wanting to force moves just to try and match division rivals tit for tat is still true. Making moves just for the sake of making them is never the right strategy even if the optics of a rival being aggressive makes fans nervous.
However, the Angels shifting into buyer mode is going to have some real reprocussions for Houston. First, the trade market is going to be more freed up now and that means more active competition in negotiations. There were a number of teams that were hoping to be able to make a play for Shohei Ohtani if he became available, but the Angels have firmly declared now that Ohtani isn't going anywhere and the Angels are making a playoff push. Teams that were holding back to make sure they had the prospects to try and make a play for Ohtani (or other Angels for that matter) are going to start looking elsewhere now.
Also, adding the Angels to the list of buyers increases the demand for the same categories of players that the Astros are looking for. Even after the Giolito trade, the Angels probably are still going to look to add another starting pitcher and they are already look at bats on the market as well. If you are following along, Houston is shopping in those same aisles.
In the end, the die has been cast and LA has made the decision to go for it and frankly, good for them for making a run at it. However, their status as buyers exacerbates the already rough demand outpacing supply problem at the deadline the Astros were having to navigate.