Question on proxy/client behaviour

During testing of various proxy servers I have found one that exhibits what I believe is bad behaviour.  I am writing this group to see if there is any kind of concensus on this.

The proxy server in question is http 1.0 compatible.  When a client sends a http 1.1 request it will modify it to use http 1.0 going to the web server.  The web server responds fine to the request, but when the proxy forwards the response to the client, the client doesn't show the web page. 

I have traced this and found that proxy is dropping the tcp PUSH flag from SOME of the response packets coming back from the server.  These "bad" packets only have the tcp ACK flag.  Response packets that are read ok by the client contain both the PUSH and ACK flags.

To me it seems that there is definitely a problem on the proxy as it should consistently send either just the ACK or both the ACK and PUSH flags with all responses.  However, should the client still try to read the payload of a packet as http data even if there isn't a PUSH flag associated with that packet?

I've looked through various RFC's and haven't found anything that says specifically if the client should or shouldn't do this.

Thanks,

Keith