During breeding season, any abnormal behavior for male Guineas can be considered normal... once their hormone levels peak, they lose their minds
Their aggression level builds as they become increasingly hormonally frustrated.
Chasing is very normal for Guineas, but usually they are chasing each other, showing off for the Hens and competing for the Alpha spot in the pecking order. Is he your only male? Does he have a Hen on a nest of eggs nearby that he could be protecting?
If he is just full of himself you might want to give him a blast with the hose or something to curb the chasing and remind him where he is in your pecking order. Stand your ground, even chase after him yelling and waving your arms at him every time he comes at you or he may let it go to his head and eventually take it a step further with his aggression towards you. Sometimes they will chase and attack other animals, and even the elderly and little kids too... so depending on your situation an attitude adjustment may be in order. (Out here on my ranch all my males know who's boss and who feeds them, lol).
The extra aggression should pass after the breeding season is over... only to return next spring tho.