Welcome to the forum!
I just saw something on tv recently, although I don't remember the details, about the origins of the swastika symbol. I don't remember what the tv show said about it, but it existed long before the nazis adopted it. It could just be seen as ancient artwork.
Although I don't think it would be a problem to show it, I can think of a couple of ways you could share the file, without the artwork being visible.
1 - Hide layer where the symbol is. Then save. Then when you attach the file, the symbol won't show (I don't think....).
2 - If that doesn't work, put an opaque square on top of it, and we can just move it off, when we open the file.
3 - After you attach the file (use the full editor, not Quick Reply) highlight the short bit of text which indicates the attachment, then click the "Ot" button. That's for making off topic comments, and they auto-hidden. Visitors have to click on it to open it.
If the swastika has perfectly squared off corners - nothing is round or fancy styles, then I guess it must be perfectly square, right? I'm thinking you could use a grid to draw the outline. With snapping, of course. Or if not a grid, then Guides. This will tell you all about Snapping, grids and guides:
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Snapping.html Or actually, you could duplicate the swastika, and drag it larger, rather than drawing another one. But it's like 6 of one and half a dozen of the other, as they say.
There is a feature which you can easily make such a path with, but it rounds off square corners, so it won't be a good solution for this. Not unless you're ok with the rounded corners? But for what it's worth, that feature is called Offset Paths, in the Paths menu.
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Paths-Editing.html#Paths-OffsetsI could probably make a little video, to show you the basics, if it would be helpful. Although I'm about to log off for today.