Madussa wasn't "allowed" to take anything anywhere. She was lucky she wasn't sued into oblivion over what she did.
Flair also wasn't allowed to take the "Big Gold Belt" to WWE. WCW did sue him and WWE - In fact, after spending a month parading that belt all over WWE TV McMahon & company had to switch and have Flair wear a tag belt at house shows which was "digitally blacked out" during his TV appearances after WCW got a temporary injunction against WWE to stop them from "damaging" their title.
McMahon was losing the Wrestling War pretty bad in late 97 and had been for almost two years. Things were extremely competitive. The Lex Luger situation was a major embarrassment for WWE as they completely believed he was re signing and staying with the company, used him prominently one night earlier on the S-Slam PPV, then suffered the indignity of his shafting The "E" with his debut on the first ever episode of Monday Nitro. Madussa, because the Womens Title was so low profile and WCW had no real Womens Wrestling Program, was a minor insult but not that bad.
In addition to the Luger embarrassment, Vince was worried about a retaliation to his antics with Flair in 1991 as far not wanting Brett to hold the title past his contract date. Flair's WCW contract expired almost a month before he left, while he was reigning World Champ, ostensibly with plans to have him lose the title to Luger at The Great AM Bash PPV. Flair continued working under the financial terms of his expired agreement while in negotiations for a new deal, but nothing was in writing. When the two sides couldn't come to terms Flair agreed to lose the title prior to the PPV to the opponent of WCW's choice (there are stories WCW chose Barry Whyndam because he & Flair had been close friends for years, since the days of Whyndam's childhood while Flair teamed with his father Blackjack Mulligan, the logic being Flair wouldn't risk no showing and damaging a good friend even though he was on good terms with Luger). In the end WCW backtracked again and simply fired Flair, who took the physical belt (which he never lost in the ring thanks to WCW's booking) in retaliation for his WCW dismissing his claims he was owed several thousand dollars in back pay related to insurance deposits he made to cover the costs of the physical belt when it was in his possession.
In the end Flair won the lawsuit and WCW paid him a settlement and he returned the physical belt. Still, Flair had turned down offers from McMahon to jump ship in both 1985 & 1989 and stayed loyal to WCW. Hart had spurned offers from WCW and always been Mr WWE and loyal to McMahon. Flair was willing to lose the belt to WCW's chosen opponent but plans could not be finalized prior to his contract expiring and WCW basically told him to leave rather than give a new deal or extend him long enough to lose the belt proper in the ring. Hart was told WWE wouldn't honor the rest of his contract and he should look for work elsewhere, his contract dates were expiring and he wasn't happy about being phased out. The final dispute over money was the last straw for Flair and his loyalty finally wavered as he took the physical belt and gave it to WWE to use on TV to humiliate WCW. Vince was worried Brett, unhappy about being asked to put over his backstage nemesis HBK, might balk (already upset about being pushed down the card and told to seek new employment elsewhere) might be willing to do something similar, especially if the money was right.
Would Brett have done it ? I doubt it although it does seem silly that he refused to lose (even with a screwjob finish) in Canada (I guess Randy Savage cant lose in FLA, Flair cant lose in NC, HHH cant lose in CT) which makes you wonder if the idea was pushed hard would he have betrayed Vince. Bottom line, Vince couldn't risk the embarrassment that his company's main title, the belt that Sammartino & Backlund as well as Flair, Hogan, & Savage had all worn, would be subjugated by WCW like what he did with their title in 1991. The embarrassment of that would have been much worse than Luger's slap in the face two years earlier. Thus Brett's offer to dropt the title in some fashion the next night after S-Series on RAW (when Brett's last contract date with WWE was already passed) was denied (much like Flair's offer to drop the WCW title prior to the Bash PPV if WCW wouldn't extend his deal and wanted him gone).