Really, it's pretty silly to insist that decades-old comic-book characters can only be portrayed one way when they've actually been portrayed many different ways over the decades. The original Alfred in the comics was a fat, buffoonish amateur detective with a working-class accent, and only came to work for Batman and Robin well after they were established as crimefighters, though his father Jarvis (yes, Jarvis) had been Thomas Wayne's butler. When Alfred appeared in the 1943 film serial, he was played by a thin, moustachioed man, and so Alfred's comics appearance was changed to match, with the explanation that he'd slimmed down at a health spa. For a time, he was occasionally known as Alfred Beagle; the name Pennyworth wasn't coined until 1969 (which is why Alan Napier's Alfred in the '60s TV series never had a last name). By that point he'd gone from lower-class to upper-class in his diction and behavior, becoming a more stereotypical English butler. Napier may have had an influence on that. Post-Crisis, he was retconned into having been Bruce's butler since childhood and his surrogate father after the Waynes died -- implicitly making him rather older than he'd been before.
Heck, in the '60s there was even a period where Alfred was apparently dead for several years, then turned out to have survived and become a deranged supervillain called the Outsider. This is a character who's been through a lot