Short answer: I'm not an expert and i don't know a tool on MacOSX that does what you want on a few clicks, impersonate a different OS.
Long answer:
Blocking/confusing OSFP might be possible with PF on MacOSX(not tested).
OpenBSD's Packet Filter has been ported by Apple (Yosemite and up). In the link's example it's on OpenBSD.
Before:
# nmap -O puffy
Starting nmap 3.48 ( http://www.insecure.org/nmap/ ) at 2003-12-02 19:14 MST
Interesting ports on puffy (192.168.0.42):
(The 1653 ports scanned but not shown below are in state: closed)
PORT STATE SERVICE
13/tcp open daytime
22/tcp open ssh
37/tcp open time
113/tcp open auth
Device type: general purpose
Running: OpenBSD 3.X
OS details: OpenBSD 3.0 or 3.3
Nmap run completed -- 1 IP address (1 host up) scanned in 24.873 seconds
After:
# nmap -O puffy
Starting nmap 3.48 ( http://www.insecure.org/nmap/ ) at 2003-12-02 22:56 MST
Interesting ports on puffy (192.168.0.42):
(The 1653 ports scanned but not shown below are in state: closed)
PORT STATE SERVICE
13/tcp open daytime
22/tcp open ssh
37/tcp open time
113/tcp open auth
No exact OS matches for host (If you know what OS is running on it, see
http://www.insecure.org/cgi-bin/nmap-submit.cgi).
TCP/IP fingerprint:
SInfo(V=3.48%P=i686-pc-linux-gnu%D=12/2%Time=3FCD7B3F%O=13%C=1)
TSeq(Class=TR%IPID=RD%TS=2HZ)
T1(Resp=Y%DF=Y%W=403D%ACK=S++%Flags=AS%Ops=MNWNNT)
T2(Resp=Y%DF=Y%W=0%ACK=S%Flags=AR%Ops=)
T3(Resp=Y%DF=Y%W=0%ACK=O%Flags=AR%Ops=)
T4(Resp=Y%DF=Y%W=4000%ACK=O%Flags=R%Ops=)
T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
PU(Resp=Y%DF=N%TOS=0%IPLEN=38%RIPTL=134%RID=E%RIPCK=F%UCK=E%ULEN=134%DAT=E)
Nmap run completed -- 1 IP address (1 host up) scanned in 27.028 seconds
Config file: /etc/pf.conf
Rules:
set block-policy return
block in log quick proto tcp flags FUP/WEUAPRSF
block in log quick proto tcp flags WEUAPRSF/WEUAPRSF
block in log quick proto tcp flags SRAFU/WEUAPRSF
block in log quick proto tcp flags /WEUAPRSF
block in log quick proto tcp flags SR/SR
block in log quick proto tcp flags SF/SF