I think the disagreement between DIY and having it installed by a pro has long passed. No one is dissing nobody here, it is only opinions from one person point of view, who is entitled to free speech.
I do believe that heat shrinking is better and secures the cable more than electrical tape and that it is more professional that way given the clean and neat installation that doesn't over time leave a sticky residue. Offended? I'm not sorry.
That is my opinion and nothing anyone can say will change it. If you are offended by ones opinion, to only help out a fellow forum member, then you shouldn't be reading this thread at all.
He is also recommending a professional business to have it done properly. Everyone has their own way of doing things and your method isn't the only "right" way. He is also recommending a professional as you are too. This I believe is neutral and has no rips on pros and DIYers.
I'm pretty sure there are more than just you and the couple who have ripped on about DIY installations who runs car security businesses. In all honesty, I could have been your potential customer at the time when I was looking for an alarm. Sent you an email via the website, didn't get a response. Asked for a little advice via PM, still no response. All I see is that you are ripping out on people who want to try DIY. Advice is better than opinion at the end of the day. Also not good for business publicity.