Typically I would agree it makes more sense grammatically to be at the end of the text, especially if you have a footnote that denotes the meaning of the asterisk. For example:
However, I would not be so adamant to say that it must be done this way. There are benefits to having the asterisk at the start. Such as that it will be the first thing the user sees when scanning the label text.
If your only concern is the alignment, then it doesn't have to be part of the label text. You could show if in a separate column of it's own so that alignment is preserved. For example:
This second option in fact opens it up for the asterisk to be replaced by an icon if desired. As you can imagine, an icon would most certainly only work by having a dedicated column to the left...
NOTE: I am not for a second suggesting using that icon/colour for a required field. it's just an example. Although perhaps you could use those icons when the user submits the form to alert them to something they have missed.
In summary, I don't think there is a fixed rule to follow. The main thing is to ensure clarity to the user, and as a UX designer, find solutions to potential problems such as the left-align concern (which you are correct to highlight). As I have hopefully demonstrated, both options can be made to work with the right design.
Also, sometimes you just have to accept who gets to make the final decision and do your best to work with that decision even if you don't agree with it.