If its a matter of presentation, where they want the page to load everything prior to displaying any content then perhaps a better solution would be to use CSS and JS to position the SEO content area to be offset by the browser height (so it is below the fold) and then locking the vertical overflow of the page until after the play process loads - then unlocking the overflow and just reseting the positioning of the SEO content.
I guess, I am not sure why your devs are proposing to load the SEO content area asynchronously after the rest of the page loads when generally SEO content is probably the lightest part of your page load.
