Is it safe to masturbate 2 weeks after having testicular abscess surgery ?

Yes, ...: With no additional info, most likely, what you reported was in fact the incision and drainage of scrotal abscess usually resulting from infected sebaceous cyst. For average young men, post-surgical resolution of the wound should heal & resolve within 7-10 days. Since such wound is not connected with genital tract, you should be able to masturbate comfortably without adverse effect to the wound.