Is this a sign that the sharks are getting out of the market?
I think you're blowing things out of proportion.
Multicoin Capital doesn't look like they're getting out of the market any time soon. My guess is that deleting those tweets means that they want a fresh new start after their recer partnership with Bitwise,
"Multicoin Capital Partners With Bitwise and Matthew Ball for Metaverse Crypto Index, Fund" (Source)About Alameda Research, latest news tells us that they're bailing out Voyager (crypto platform that collapsed though not as hard as Celcius network) so, I'd say they still have faith in the crypto market.