Yes, because whatever business value he could get from adding your app his website is so obviously and most certainly not worth that insane 63K (MINIFIED!!!) increase in page size, bandwidth, and DOM performance.
On a side note, I wonder if he has fever dreams about all of the inefficient WordPress sites basically running the internet today…
Or maybe it’s just that his side project is a browser extension that blocks any website larger than 64K in total size and your app would have put him over the top.
Seriously, wow.