No. I don't think we need LaTeX here.
For very simple cases e.g. πR(R ⋈ S)
as in my answer here, the normal character set is adequate.
On the odd occasion where e.g. complex relational algebra is required, an image should suffice:

The above was generated using this tool, mentioned in this meta.SE answer.
-- Source
\Pi_{A,B}(\sigma_{r.C=s.C})(r \times s)\otimes\sigma_{D > 20}(s))
(That is my first ever effort at LaTeX formatting)
There is also mathurl.com and probably many others.
If it were a "simple checkbox" to enable this for Database Administrators without any consequences at all, I'd probably say "yeah, OK, why not" but I don't think that is the case.
The case is clearly pretty compelling for sites like Mathematics, but not here.
To address a point brought up in a comment to the question, I don't think this is the solution for the 'tables' issue either (assuming for a moment that it is an issue). How many people that currently struggle with an ASCII table (or other workaround) would be able to generate the required LaTex? Not many, I would suggest.