Is that something that's even possible? Have you seen it done anywhere else? I think it would be great if it's something that CAN be done, and for the same reasons you stated...especially for someone brand new to the forum, who has just arrived for help on his or her high school homework problem, the last thing they're going to do is spend time learning latex before posting their question.
IF it's possible, I would have just two concerns that might both be addressed with a single solution, and stem from a common problem:
If a student is making mistakes in typing the problem (i.e., not properly using parentheses to group things when typing an equation on a single line instead of being able to use all the symbols on the written page in front of them), then
1) If the HW helpers see that they are not using latex, it's an obvious clue that the equation may be transcribed improperly, and they will know to prompt to find out how parts are grouped in the original problem, and
2) If that problem gets automatically converted/formatted by latex, the student may be equally baffled as to why their equation suddenly appears so strangely.
Now, in the second case, we might hope that would be a clue to the student that they've mistyped something, but, having spent enough time around here with the variety of students who come and go looking for help, I know that is not realistic with all but the most astute students.
So, perhaps having something that allows the student to choose whether or not to use latex formatting as an option might help. It would probably be entirely useless to put in a button that reads, "Convert to LaTex" because those who need that won't have a clue what latex is. So, it would have to be something like, "Format Equations" which then brings them to a preview page before posting with an added prompt before submission, like, "Is the formatting correct?" with buttons saying, "Yes, submit" or "No, I need to edit."