Sadiq,
Most of the time guys like the one you encountered (even though he looked like a big rugby player type) has got more bark than bite my friend. Or like us Afrikaans boys say "hy's meer bek as binnegoed".
Reality is that fishing is a sport that you are supposed to enjoy by relaxing and appreciate the fact that you have the privilage of spending time in the beauty of nature. It is also supposed to be a selfless sport for the sake of educating everyone who will make up the future of fishing. Most of the times I've been at the fishing waters I find that I end up meeting at least one person that shares the same passion as I have for this lovely sport and during my stay at the venue I consider that person a friend regardless of size, race, experience etc. (Might sound like a bit of a tree hugger, flower child or monk). What some people are supposed to enjoy, they end up taking way too seriously.
You might find that this individual was sulking because the fish weren't coming to the party as far as his success in catching anything is concerned, or he was unhappy with his last cast, or the kids or wife were distracting him from finding his rythm or routine, or he brought life's problems along to the fishing water with him and was just looking for someone to take his frustrations out on.
If the lines were crossed from poor casting or windy conditions a couple times it shouldn't be a problem to a guy that understands the sport as a whole. If it happens multiple times where lines are crossed due to your fishing neighbour's lack of ability to cast properly then it would be appropriate to discuss the matter like gentlemen and use such an opportunity to educate that person so that they may too enjoy it to the full. Not becoming verbally abusive or pick a fight by mumbling to your wife or fishing partner about how you are going to stuff the guy up etc. He probably packed his ego and probably a bottle of 43% alcohol volume superhero juice in his fishing box instead of his humility.
I'm not a small oke myself standing 1.78m tall and weighing in at 110kg and I've had a couple years training in karate, boxing, atemi jujitsu and basic self defence. Not that any of this matters and I don't broadcast it in the friendship and fishing circles that I frequent as its not about the fight, but being able to walk away from a life threatening situation to live and fish another day and resolving problems without having to lay a finger on anyone.
But anyways all these wise words and the long life lesson that I've just unpacked here for you and what I'm actually getting at comes down to don't let people such as this oke intimidate and threaten you. Walk up to a guy like that, introduce yourself and start making small talk and just mention during the convo "I realise that my last cast came a bit close to where your line has been positioned, the line slipped off my finger, if it crossed I'm sorry, would you prefer that I re-cast the line or can we check it if and when either one of us gets a pick up?" Nine times out of ten he'll say "No leave it we'll sort it out if either one of us gets a reel run". If he's not to loaded on the superhero juice he'd probably even feel embarrased and feel bad for making a fuss or mumbling about how he was gonna stuff you up. Most of us don't like egotistic chaps like these.
I believe that even the most experienced fisherman learns something new on every fishing trip they attend. Never be too embarrased or too proud to ask. The only stupid question when it comes to fishing is the one left unasked.
Enjoy the fishing, the learning and the experience. Tight lines mate.:fishn