You'll probably get a more authoratitive answer from one of the McAfee guys on this forum, but I guess it depends what you mean by reverse proxy.
If you are speaking about caching, then I don't think so. The Squid caching proxy service was retired when version 7 came out.
But, the HTTP and HTTPS services are sill transparent proxies in essence - because there is no direct contact between the client and the server. If you use these services in an inbound rule you will ensure that the traffic using this rule adheres to the appropriate protocol standard and you can apply an application defense definition to the rule which will allow you to govern exactly how the protocol behaves. So if there's anything, which is otherwise legitimate within the protocol, which you don't want external users to do, you can configure the application defense in such a way that these elements are disabled.
one customer of ours if planning to replace their end of life TMG. and i was wondering if Sidewinder is the right candidate for replacement.
what i mean by reverse proxy here is to terminate incoming connections to webservers, SSL offloading, basic load balancing, etc..
I have heard and read that Palo Alto can act as a reverse proxy, it can even act as an SSL vpn gateway.
The firewall can terminate incoming connections to webservers, it can do SSL-offloading, it has basic load-sharing (not balancing).
I imagine by 'reverse proxy' you mean a proxy for external connections to come inbound (vs. proxying outbound connections). If so, yes, the firewall is a reverse proxy.