Illegal use of H1 Tag?

This is not my site but i noticed this site has high rankings and has placed an H1 tag at the top of their site:

it appears to be the only h1 tag on the page, but wondering if this sort of activity is frowned upon?

Why would it be frowned upon?
H1 is the first heading on a page and its where it should be…

Google doesn’t give out site building tickets. If they don’t like it, they will reflect their opinion in the rankings.

If by that you mean site building tips & guidelines, then you’re wrong.

I never said tips. I said tickets / infractions. If you don’t build it to the standard, you are only hurting yourself. If you try and beat them and use deceptive methods, then it will be reflected in the serps, ie… poor ranking, no ranking or a penalty.

H1 tag could be used in content because when crawler visits it’s come in notice to it that the site is what about. So it’s good if you use H1 tag in your content in the starting only. But it should not be used more then once.If you think that there are some content which should be highlighted then you can use bold or italics.