What makes me think that Bozon is 3 fighter pilots, one of whom has shot down a Mig 29, and two others both over 2000 hours, one of those having flown nearly every fighter in Nato's inventory except the F22, including the Grippen, Typhoon as the main development pilot on their radar and sensor displays, the F18, F16, and F5, TOLD me so. Simple as that.
If you get into these arguments with amateurs like me and you on the internet, you can go round and round forever based on opinions that are likewise read on the internet. If I'm told something by people who actually do it for a living, and have been instructors at the best schools on the planet for doing it, I take their word over anyone else. Do you know anybody who has flown the Typhoon and been involved in it since the beginning, and heard their opinion on how it stacks up versus American stealth fighters? I'll gladly PM you the pilot's names if you wish, I graduated from school with one, having grown up with him since I was 4, and met the other 2 through him, and he's currently a Major in the RCAF and has over 2500 hours in the Hornet, 300+ of that combat time, and will be the RCAF test pilot for the F35 as well, and is currently in the USA flying it right now.
You are correct that there is many ways to avoid detection, just flying certain routes and profiles was a big part of the F117's stealth capability so they say. "They" also say Israel has a magic box that makes their non stealth aircraft invisible too. Who knows what the future will bring, but as of right now, I'll go with what information I was told by pilots that do it for a living every day.