I guess that it's just mechanical error,
because in _Layout.cshtml file
https://github.com/aspnet/live.asp.net/blob/dev/src/live.asp.net/Views/Shared/_Layout.cshtml#L21
we have
<link rel="stylesheet" href="~/css/site.css" asp-file-version="true" />"
instead
"<link rel="stylesheet" href="~/css/site.min.css" asp-file-version="true" />"
resulting, on production we get not minified file.
I guess that it's just mechanical error, because in _Layout.cshtml file https://github.com/aspnet/live.asp.net/blob/dev/src/live.asp.net/Views/Shared/_Layout.cshtml#L21 we have
<link rel="stylesheet" href="~/css/site.css" asp-file-version="true" />"
instead"<link rel="stylesheet" href="~/css/site.min.css" asp-file-version="true" />"
resulting, on production we get not minified file.