AV is supported in both 32 and 64 but the definition set for both are diffrent and are centrally managed by sepm to overcome the limitation of version 10 and earlier
PTP --The Proactive Threat Scan might increase the number of False Positives as it is just behaviour based scanning and since SEP is an Enterprise Product nobody likes False Positives on there critical servers or infact any servers.
Application and Device control and Tamper Protection --These are the two components that are not supported on 64 bits mainly because the architecture of 64 bit systems are diffrent as compared to 32 bit systems and till date there might not have been huge demand for these to features on 64 bit systems as they are fairly more secure when compared to 32 bit systems.
Network Threat Protection is basically something that comes between Network and Transport layer of OSI layer so it will in the similar way in both 32 bit and 64 bit systems.