Correct, this is the intended method.
To quote the privileges page on the matter, the following is what is shown on the user card:
- A larger resolution of your avatar
- Your display name linked to your profile
- Your reputation and badges
- Your Location, if you have entered one on your profile
- A link to your Website, if you have entered one on your profile
- Your About Me section. Up to the first 298 characters will be displayed as the meat of your expanded usercard. HTML links and linebreaks/paragraphs will be rendered, but not formatting such as bold.
- Any additional HTML links will be displayed and linked at the bottom of the expanded usercard. This does not repeat any links that are already shown in the previous part.
It is only the second-to-last bullet that is replaced by using
<!-- summary: text -->. The last point is not affected by it, so any HTML links will be shown at the bottom. Note that because you can't include any HTML links in a summary block (on account of being inside an HTML comment, it breaks), this means that all HTML links in your About Me section will be rendered in this fashion.