I don't know though.
I completely get that point of it being "inflated" because of falsely attributing things like the Tamate Box explosion, the alliance of Germa and the Firetanks to him specifically.
But then again it may not be that inflated, or too off to say he deserves to be mentioned in the same sentence as people like Teach and Kaido.
Remember, the bounty is about the evaluation of how much the Government is willing to pay to get this dangerous criminal. It's a meter of how many fucks they give.
Even taking out the aspects Morgans claimed was Luffy's doing, when you look at Luffy's track record of upturning entire countries when he visits them, it does make a bit of sense.
If we remember when Luffy got his first bounty, it was decided with a large group of Marines including Commodores and Vice Admirals. So if we're assuming it's their perspective going into deciding these numbers, they're looking at this man that keeps getting strong allies(this rookie got Whitebeard, Crocodile, Iva, and Jimbei to help him out. A kid did this), keeps fucking up the status quo wherever he goes(The WG Trifecta he fucked up between Enies Lobby and the War), has taken down multiple Warlords, directly hurting the balance of powers.
So while the newspaper is hyping Luffy up, I don't know if that's exactly influencing the bounty number itself. Since the timeskip Luffy has fucked this balance up even further and only in a few short months at the most. Since he's been back he allied with one Warlord that lost his position as a result, beat another one which crippled a huge criminal empire and embarrassed the Government as a result, then goes and screw with an Emperor.
I'd say the evaluation is looking at his progress in a short amount of time more so than Morgans report with this. The other Supernova have done bad things, but Luffy has directly upset the balance of powers more than anyone, and is the only one that directly attacked all three of the World Government's main strongholds. From their perspective, he probably comes off as the most dangerous to them specifically.